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  • Articles  (1,409,091)
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  • Articles  (1,409,091)
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  • 1
    Electronic Resource
    Electronic Resource
    Tree-unitarity bounds for THDM Higgs masses revisited (2006)
    Springer
    The European physical journal 46 (2006), S. 81-91 
    Details
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: AbstractWe have reconsidered theoretical upper bounds on the scalar boson masses within the two-Higgs-doublet model (THDM), employing the well-known technical condition of tree-level unitarity. Our treatment provides a modest extension and generalization of some previous results of other authors. We present a rather detailed discussion of the solution of the relevant inequalities and offer some new analytic formulae as well as numerical values for the Higgs mass bounds in question. A comparison is made with the earlier results on the subject that can be found in the literature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1140/epjc/s2006-02472-3
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  • 2
    Electronic Resource
    Electronic Resource
    Effective-Lagrangian approach to γγ→WW II: Results and comparison with e+e-→WW (2006)
    Springer
    The European physical journal 46 (2006), S. 93-105 
    Details
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: AbstractWe present a study of anomalous electroweak gauge-boson couplings that can be measured in e+e- and γγ collisions at a future linear collider like ILC. We consider the gauge-boson sector of a locally SU(2)×U(1) invariant effective Lagrangian with ten dimension-six operators added to the Lagrangian of the standard model. These operators induce anomalous three-gauge-boson and four-gauge-boson couplings and an anomalous γγH coupling. We calculate the reachable sensitivity for the measurement of the anomalous couplings in γγ→WW. We compare these results with the reachable precision in the reaction e+e-→WW on the one hand and with the bounds that one can obtain from high-precision observables in Z decays on the other hand. We show that one needs both the e+e- and the γγ modes at an ILC to constrain the largest possible number of anomalous couplings and that the Giga-Z mode offers the best sensitivity for certain anomalous couplings.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1140/epjc/s2006-02474-1
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  • 3
    Electronic Resource
    Electronic Resource
    Flavor coupled with chiral oscillations in the presence of an external magnetic field (2006)
    Springer
    The European physical journal 46 (2006), S. 113-122 
    Details
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: AbstractReporting to the Dirac wave-packet prescription where it is formally assumed the fermionic nature of the particles, we shall demonstrate that chiral oscillations implicitly aggregated to the interference between positive and negative frequency components of mass eigenstate wave-packets introduce some small modifications to the standard neutrino flavor conversion formula. Assuming the corresponding spinorial solutions of a ‘modified’ Dirac equation, we are specifically interested in quantifying flavor coupled with chiral oscillations for a fermionic Dirac-type particle (neutrino) non-minimally coupling with an external magnetic field B . The viability of the intermediate wave-packet treatment becomes clear when we assume B orthogonal/parallel to the direction of the propagating particle.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1140/epjc/s2006-02502-2
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  • 4
    Electronic Resource
    Electronic Resource
    Production properties of $K^\star(892)^\pm$ vector mesons and their spin alignment as measured in the NOMAD experiment (2006)
    Springer
    The European physical journal 46 (2006), S. 69-79 
    Details
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: AbstractFirst measurements of $K^\star(892)^\pm$ mesons production properties and their spin alignment in $\nu_\mu$ charged current (CC) and neutral current (NC) interactions are presented. The analysis of the full data sample of the NOMAD experiment is performed in different kinematic regions. For ${K^\star}^+$ and ${K^\star}^-$ mesons produced in $\nu_\mu$ CC interactions and decaying into $K^0 \pi^\pm$ we have found the following yields per event: $(2.6\pm0.2(\text{stat.})\pm0.2(\text{syst.}))\%$ and $(1.6\pm0.1(\text{stat.})\pm0.1(\text{syst.}))\%$ respectively, while for the ${K^\star}^+$ and ${K^\star}^-$ mesons produced in $\nu\text{NC}$ interactions the corresponding yields per event are: $(2.5\pm0.3(\text{stat.})\pm0.3(\text{syst.}))\%$ and $(1.0\pm0.3(\text{stat.})\pm0.2(\text{syst.}))\%$ . The results obtained for the $\rho_{00}$ parameter, $0.40\pm0.06(\text{stat.})\pm0.03(\text{syst.})$ and $0.28\pm0.07(\text{stat.})\pm0.03(\text{syst.})$ for $K^\star(892)^+$ and $K^\star(892)^-$ produced in $\nu_\mu$ CC interactions, are compared to theoretical predictions tuned on LEP measurements in $e^+e^-$ annihilation at the $Z^0$ pole. For $K^\star(892)^+$ mesons produced in $\nu\text{NC}$ interactions the measured $\rho_{00}$ parameter is $0.66\pm0.10(\text{stat.})\pm0.05(\text{syst.})$ .
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1140/epjc/s2006-02500-4
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  • 5
    Electronic Resource
    Electronic Resource
    The QCD pomeron in ultraperipheral heavy ion collisions: V. Double vector meson production in the BFKL approach (2006)
    Springer
    The European physical journal 46 (2006), S. 219-224 
    Details
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: AbstractIn this work the double vector meson production in ultraperipheral heavy ion collisions is investigated within the BFKL approach. The integrated cross sections and event rates for the processes $AA\rightarrow V_1 V_2 AA$ ( $V_i=\rho, \omega, \phi, J/\Psi, \Upsilon$ ) are computed and theoretical estimates for scattering on both light and heavy nuclei are given for energies of RHIC and LHC.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1140/epjc/s2006-02473-2
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  • 6
    Electronic Resource
    Electronic Resource
    Ultra low momentum neutron catalyzed nuclear reactions on metallic hydride surfaces (2006)
    Springer
    The European physical journal 46 (2006), S. 107-111 
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    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: AbstractUltra low momentum neutron catalyzed nuclear reactions in metallic hydride system surfaces are discussed. Weak interaction catalysis initially occurs when neutrons (along with neutrinos) are produced from the protons that capture “heavy” electrons. Surface electron masses are shifted upwards by localized condensed matter electromagnetic fields. Condensed matter quantum electrodynamic processes may also shift the densities of final states, allowing an appreciable production of extremely low momentum neutrons, which are thereby efficiently absorbed by nearby nuclei. No Coulomb barriers exist for the weak interaction neutron production or other resulting catalytic processes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1140/epjc/s2006-02479-8
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  • 7
    Electronic Resource
    Electronic Resource
    A remark on the motivic Galois group and the quantum coadjoint action (2006)
    Springer
    The European physical journal 46 (2006), S. 269-275 
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    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: AbstractIt has been suggested that the Grothendieck–Teichmüller group GT should act on the Duflo isomorphism of su(2), but the corresponding realization of GT turned out to be trivial. We show that a solvable quotient of the motivic Galois group – which is supposed to agree with GT – is closely related to the quantum coadjoint action on $U_q(sl_2)$ for q a root of unity, i.e. in the quantum group case one has a nontrivial realization of a quotient of the motivic Galois group. From a discussion of the algebraic properties of this realization we conclude that in more general cases than $U_q(sl_2)$ it should be related to a quantum version of the motivic Galois group. Finally, we discuss the relation of our construction to quantum field and string theory and explain what we believe to be the ‘physical reason’ behind this relation between the motivic Galois group and the quantum coadjoint action. This might be a starting point for the generalization of our construction to more involved examples.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1140/epjc/s2006-02487-8
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  • 8
    Electronic Resource
    Electronic Resource
    Dual parameterization of generalized parton distributions and a description of DVCS data (2006)
    Springer
    The European physical journal 46 (2006), S. 151-156 
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    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: AbstractWe discuss a new leading-order parameterization of generalized parton distributions of the proton, which is based on the idea of duality. In its minimal version, the parameterization is defined by the usual quark singlet parton distributions and the form factors of the energy-momentum tensor. We demonstrate that our parameterization describes very well the absolute value, the Q2-dependence and the W-dependence of HERA data on the total DVCS cross section and contains no free parameters in the HERA kinematics. The parameterization suits the low-xBj region especially well, which allows us to advocate it as a better alternative to the frequently used double distribution parameterization of the GPDs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1140/epjc/s2006-02491-0
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  • 9
    Electronic Resource
    Electronic Resource
    Stationary phase corrections in the process of bosonization of multi-quark interactions (2006)
    Springer
    The European physical journal 46 (2006), S. 225-233 
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    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: AbstractThe functional integration over the auxiliary bosonic variables of cubic order related with the effective action of the Nambu–Jona–Lasinio model with ’t Hooft term has recently been obtained in the form of a loop expansion. Even numbers of loops contribute to the action, while odd numbers of loops are assigned to the measure. We consider the two-loop corrections and analyse their effect on the low-lying pseudoscalar and scalar mass spectra, quark condensates and weak decay constants. The results are compared to the leading order calculations and other approaches.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1140/epjc/s2006-02488-7
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  • 10
    Electronic Resource
    Electronic Resource
    New result on the measurement of the direct photon emission in K+→π+π0γ decay (2006)
    Springer
    The European physical journal 46 (2006), S. 61-67 
    Details
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: AbstractWe present a new result on the K+→π+π0γ decay measurement using stopped kaons. The best fit to the decay spectrum comprised of 10 k events gives a branching ratio for the direct photon emission of [3.8±0.8 (stat)±0.7 (syst)]×10-6 in the π+ kinetic energy region of 55 to 90 MeV. This result has been obtained with the assumption that there is no component due to interference with the inner bremsstrahlung.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1140/epjc/s2006-02492-y
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  • 11
    Electronic Resource
    Electronic Resource
    On bound states of photons in noncommutative U(1) gauge theory (2006)
    Springer
    The European physical journal 46 (2006), S. 235-245 
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    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. We consider the possibility that photons of noncommutative U(1) gauge theory can make bound states. Using the potential model, developed based on the constituent gluon picture of QCD glue-balls, arguments are presented in favor of the existence of these bound states. The basic ingredient of the potential model is that the self-interacting massless gauge particles may get mass by the inclusion of non-perturbative effects.PACS. 02.40.Gh, 11.10.Nx, 12.20.-m
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1140/epjc/s2005-02465-8
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  • 12
    Electronic Resource
    Electronic Resource
    Screening of heavy quark free energies at finite temperatureand non-zero baryon chemical potential (2006)
    Springer
    The European physical journal 46 (2006), S. 179-189 
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    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. We analyze the dependence of heavy quark free energies on the baryon chemical potential μb in 2-flavor QCD by performing a 6th order Taylor expansion in the chemical potential which circumvents the sign problem. The bare quark mass at $\hat m / T = 0.4$ corresponds to a pion mass of about 770 MeV and is thus not in the range of physical quark masses but the quark mass dependence is known to be small above Tc. At Nτ = 4 the lattices are coarse, however, we are using improved (p4 staggered) fermions. The Taylor expansion coefficients of color singlet and color averaged free energies are calculated and from this the expansion coefficients for the corresponding screening masses are determined. We find that for small μb the free energies of a static quark-antiquark pair decrease in a medium with a net excess of quarks and that screening is well described by a screening mass which increases with increasing μb. The μb-dependent corrections to the screening masses are well described by perturbation theory for T ≳ 2Tc. In particular, we find for all temperatures above Tc that the expansion coefficients for singlet and color averaged screening masses differ by a factor 2.PACS. 11.15.Ha, 11.10.Wx, 12.38Gc, 12.38.Mh
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1140/epjc/s2005-02462-y
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  • 13
    Electronic Resource
    Electronic Resource
    High energy evolution of soft gluon cascades (2006)
    Springer
    The European physical journal 46 (2006), S. 135-145 
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    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. In this paper we derive an evolution equation for the gluon density in soft gluon cascades emitted from any colored source, in the leading logarithmic approximation of perturbative QCD. We show that this equation has the same form as the BFKL equation in the forward case. An explicit expression for the total cascade wavefunction involving an arbitrary number of soft gluons is obtained. Renormalization of the colored source wavefunction turns out to be responsible for the reggeization of the source.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1140/epjc/s2005-02468-5
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  • 14
    Electronic Resource
    Electronic Resource
    The Dalitz decay π0 → e+e– γ revisited (2006)
    Springer
    The European physical journal 46 (2006), S. 191-217 
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    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. The amplitude of the Dalitz decay π0 → e+e– γ is studied and its model-independent properties are discussed in detail. A calculation of radiative corrections is performed within the framework of two-flavor chiral perturbation theory, enlarged by virtual photons and leptons. The lowest meson dominance approximation, motivated by large NC considerations, is used for the description of the π0 –γ*–γ* transition form factor and for the estimate of the NLO low energy constants involved in the analysis. The two photon reducible contributions are included and discussed. Previous calculations are extended to the whole kinematical range of the soft photon approximation, thus allowing for the possibility to consider various experimental situations and observables.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1140/epjc/s2005-02466-7
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  • 15
    Electronic Resource
    Electronic Resource
    Forward jet production in deep inelastic scattering at HERA (2006)
    Springer
    The European physical journal 46 (2006), S. 27-42 
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    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. The production of forward jets has been measured in deep inelastic ep collisions at HERA. The results are presented in terms of single differential cross sections as a function of the Bjorken scaling variable (xBj) and as triple differential cross sections d3σ/dxBjdQ2 $dp_{t,{\rm jet}}^2$ , where Q2 is the four momentum transfer squared and $p_{t,{\rm jet}}^2$ is the squared transverse momentum of the forward jet. Also cross sections for events with a di-jet system in addition to the forward jet are measured as a function of the rapidity separation between the forward jet and the two additional jets. The measurements are compared with next-to-leading order QCD calculations and with the predictions of various QCD-based models.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1140/epjc/s2005-02471-x
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  • 16
    Electronic Resource
    Electronic Resource
    Evaluating massive planar two-loop tensor vertex integrals (2006)
    Springer
    The European physical journal 46 (2006), S. 157-178 
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    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: AbstractUsing the parallel/orthogonal space method, we calculate the planar two-loop three-point diagram and two rotated reduced planar two-loop three-point diagrams. Together with the crossed topology, these diagrams are the most complicated ones in the two-loop corrections necessary, for instance, for the decay of the Z0 boson. Instead of calculating particular decay processes, we present a new algorithm which allows us to perform arbitrary next-to-next-to-leading order (NNLO) calculations for massive planar two-loop vertex functions in the general mass case. All integration steps up to the last two are performed analytically and will be implemented under xloops as part of the Mainz xloops-GiNaC project. The last two integrations are done numerically using methods like VEGAS and Divonne. Thresholds originating from Landau singularities are found and discussed in detail. In order to demonstrate the numerical stability of our methods we consider particular Feynman integrals which contribute to different physical processes. Our results can be generalized to the case of the crossed topology.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1140/epjc/s2006-02478-9
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  • 17
    Electronic Resource
    Electronic Resource
    Lorentz symmetry breaking and planar effects from non-linear electrodynamics (2006)
    Springer
    The European physical journal 46 (2006), S. 247-254 
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    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: AbstractWe propose a modification of standard linear electrodynamics in four dimensions, where effective non-trivial interactions of the electromagnetic field with itself and with matter fields induce Lorentz violating Chern–Simons terms. This yields two consequences: it provides a more realistic and general scenario for the breakdown of Lorentz symmetry in electromagnetism and it may explain the effective behavior of the electromagnetic field in certain planar phenomena (for instance, Hall effect). A number of proposals for non-linear electrodynamics is discussed along the paper. Important physical implications of the breaking of Lorentz symmetry, such as optical birefringence and the possibility of having conductance in the vacuum are commented on.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1140/epjc/s2006-02483-0
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  • 18
    Electronic Resource
    Electronic Resource
    Supersymmetry parameter analysis: SPA convention and project (2006)
    Springer
    The European physical journal 46 (2006), S. 43-60 
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    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. High-precision analyses of supersymmetry parameters aim at reconstructing the fundamental supersymmetric theory and its breaking mechanism. A well defined theoretical framework is needed when higher-order corrections are included. We propose such a scheme, Supersymmetry Parameter Analysis SPA, based on a consistent set of conventions and input parameters. A repository for computer programs is provided which connect parameters in different schemes and relate the Lagrangian parameters to physical observables at LHC and high energy e + e- linear collider experiments, i.e., masses, mixings, decay widths and production cross sections for supersymmetric particles. In addition, programs for calculating high-precision low energy observables, the density of cold dark matter (CDM) in the universe as well as the cross sections for CDM search experiments are included. The SPA scheme still requires extended efforts on both the theoretical and experimental side before data can be evaluated in the future at the level of the desired precision. We take here an initial step of testing the SPA scheme by applying the techniques involved to a specific supersymmetry reference point.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1140/epjc/s2005-02460-1
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  • 19
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    Generalized gauge theories with nonunitary parallel transport: * General relativity with cosmological constant as an example (2006)
    Springer
    The European physical journal 46 (2006), S. 255-267 
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    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. In gauge theories parallel transporters (PTs) $\mathcal{U}(C)$ along paths C play an important role. Traditionally they are unitary or pseudoorthogonal maps between vector spaces. We propose to abandon unitarity of parallel transporters and with it the a priori assumption of metricity in general relativity. A *-operation on parallel transporters serves as a substitute for it, and this *-operation is proven to be unique on group theoretical grounds. The vierbein and the spin connection appear as distinguishable parts of a single de Sitter gauge field with field strength F. The action takes the form $\frac{3}{16\pi G\Lambda}\int\text{tr}(\boldsymbol{F}\wedge\boldsymbol{F}i\boldsymbol{\gamma}_{5})$ and both the Einstein field equations with arbitrarily small but nonvanishing cosmological constant Λ and the condition of vanishing torsion are obtained from it. The equation of motion for classical massive bodies turns out to be de Sitter covariant.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1140/epjc/s2005-02443-2
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  • 20
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    Unintegrated gluon distributions and Higgs boson productionin proton-proton collisions (2006)
    Springer
    The European physical journal 46 (2006), S. 123-134 
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    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. Inclusive cross sections for Higgs boson production in proton-proton collisions are calculated in the formalism of unintegrated gluon distributions (UGDFs). Different UGDFs from the literature are used. Although they were constructed in order to describe the HERA deep-inelastic scattering F2 data, they lead to surprisingly different results for Higgs boson production. We present both the two-dimensional invariant cross section as a function of Higgs boson rapidity and transverse momentum, as well as the corresponding projections on rapidity or transverse momentum. We quantify the differences between different UGDs by applying different cuts on interrelations between the transverse momentum of the Higgs and the transverse momenta of both fusing gluons. We focus on the large rapidity region. The interplay of the gluon-gluon fusion and weak-boson fusion in rapidity and transverse momentum is discussed. We find that above pt ∼ 50–100 GeV the weak-gauge boson fusion dominates over gluon-gluon fusion.PACS. 12.38.Bx,12.38.Cy,13.85.Qk,14.70.Hp,14.80.Bn
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    URL: http://dx.doi.org/10.1140/epjc/s2005-02464-9
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  • 21
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    Transversity and its accompanying T-odd distribution from Drell–Yan processes with pion-proton collisions (2006)
    Springer
    The European physical journal 46 (2006), S. 147-150 
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    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: AbstractThis paper studies the possibility of direct extraction of the transversity and its accompanying T-odd parton distribution function (PDF) from Drell–Yan (DY) processes with unpolarized pion beam and with both unpolarized and transversely polarized proton targets. At present, such an extraction can be performed with the COMPASS experiment at CERN. The preliminary estimations performed for the COMPASS kinematic region demonstrate that it is quite realistic to extract both transversity and its accompanying T-odd PDF under COMPASS conditions.
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    URL: http://dx.doi.org/10.1140/epjc/s2006-02490-1
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  • 22
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    A measurement of the tau hadronic branching ratios (2006)
    Springer
    The European physical journal 46 (2006), S. 1-26 
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    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: AbstractThe exclusive and semi-exclusive branching ratios of the τ lepton hadronic decay modes ( $h^- \nu_\tau$ , $h^- \pi〈Superscript〉0〈/Superscript〉 \nu_\tau$ , $h^-\pi^0 \pi^0\nu_\tau$ , $h^- \geq2 \pi^0 \nu_\tau$ , $h^- \geq3 \pi^0 \nu_\tau$ , $2h^- h^+ \nu_\tau$ , $2h^- h^+\pi^0\nu_\tau$ , $2h^- h^+ \geq2 \pi^0 \nu_\tau$ , $3h^- 2h^+\nu_\tau$ and $3h^- 2h^+ \geq1 \pi^0 \nu_\tau$ ) were measured with data from the DELPHI detector at LEP.
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    URL: http://dx.doi.org/10.1140/epjc/s2006-02494-9
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  • 23
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    Isolation and Characterization of a Pseudomonas Oleovorans Degrading the Chloroacetamide Herbicide Acetochlor (2006)
    Springer
    Biodegradation 17 (2006), S. 219-225 
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    ISSN: 1572-9729
    Keywords: acetochlor ; degradation ; isolation ; Pseudomonas oleovorans
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract To date, no pure bacterial cultures that could degrade acetochlor have been described. In this study, one strain of microorganism capable of degrading acetochlor, designated as LCa2, was isolated from acetochlor-contaminated soil. The strain LCa2 is Pseudomonas oleovorans according to the criteria of Bergey’s manual of determinative bacteriology and sequence analysis of the partial 16S rRNA gene. Optimum growth temperature and pH were 35 °C and 8.0, respectively. The strain could degrade 98.03% of acetochlor treated at a concentration of 7.6 mg l−1 after 7 days of incubation and could tolerate 200 mg l−1 of acetochlor. When the acetochlor concentration became higher, the degradation cycle became longer. The acetochlor biodegradation products were identified by GC–MS based on mass spectral data and fragmentation patterns. The main plausible degradative pathways involved dechlorination, hydroxylation, N-dealkylation, C-dealkylation and dehydrogenation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s10532-005-4220-0
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  • 24
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    2,4-Dichlorophenoxyacetic Acid (2,4-D) Utilization by Delftia acidovorans MC1 at Alkaline pH and in the Presence of Dichlorprop is Improved by Introduction of the tfdK Gene (2006)
    Springer
    Biodegradation 17 (2006), S. 263-273 
    Details
    ISSN: 1572-9729
    Keywords: Delftia acidovorans MC1 ; 2,4-dichlorophenoxyacetic acid (2,4-D) ; 2-(2,4-dichlorophenoxy) propanoic acid (2,4-DP) ; effect of tfdK gene ; simultaneous utilization of 2,4-D and 2,4-DP ; uptake characteristics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Growth of Delftia acidovorans MC1 on 2,4-dichlorophenoxyacetic acid (2,4-D) and on racemic 2-(2,4-dichlorophenoxy)propanoic acid ((RS)-2,4-DP) was studied in the perspective of an extension of the strain’s degradation capacity at alkaline pH. At pH 6.8 the strain grew on 2,4-D at a maximum rate (μmax) of 0.158 h−1. The half-maximum rate-associated substrate concentration (Ks) was 45 μM. At pH 8.5 μmax was only 0.05 h−1 and the substrate affinity was mucher lower than at pH 6.8. The initial attack of 2,4-D was not the limiting step at pH 8.5 as was seen from high dioxygenase activity in cells grown at this pH. High stationary 2,4-D concentrations and the fact that μmax with dichlorprop was around 0.2 h−1 at both pHs rather pointed at limited 2,4-D uptake at pH 8.5. Introduction of tfdK from D. acidovorans P4a by conjugation, coding for a 2,4-D-specific transporter resulted in improved growth on 2,4-D at pH 8.5 with μmax of 0.147 h−1 and Ks of 267 μM. Experiments with labeled substrates showed significantly enhanced 2,4-D uptake by the transconjugant TK62. This is taken as an indication of expression of the tfdK gene and proper function of the transporter. The uncoupler carbonylcyanide m-chlorophenylhydrazone (CCCP) reduced the influx of 2,4-D. At a concentration of 195 μM 2,4-D, the effect amounted to 90% and 50%, respectively, with TK62 and MC1. Cloning of tfdK also improved the utilization of 2,4-D in the presence of (RS)−2,4-DP. Simultaneous and almost complete degradation of both compounds occurred in TK62 up to D = 0.23 h−1 at pH 6.8 and up to D = 0.2 h−1 at pH 8.5. In contrast, MC1 left 2,4-D largely unutilized even at low dilution rates when growing on herbicide mixtures at pH 8.5.
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    URL: http://dx.doi.org/10.1007/s10532-005-6894-8
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    Isolation of Fenitrothion-degrading Strain Burkholderia sp. FDS-1 and Cloning of mpd Gene (2006)
    Springer
    Biodegradation 17 (2006), S. 275-283 
    Details
    ISSN: 1572-9729
    Keywords: biodegradation ; Burkholderia ; fenitrothion ; mpd gene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A short rod shaped, gram-negative bacterium strain Burkholderia sp. FDS-1 was isolated from the sludge of the wastewater treating system of an organophosphorus pesticides manufacturer. The isolate was capable of using fenitrothion as the sole carbon source for its growth. FDS-1 first hydrolyzed fenitrothion to 3-methyl-4-nitrophenol, which was further metabolized to nitrite and methylhydroquinone. The addition of other carbon source and omitting phosphorus source had little effect on the hydrolysis of fenitrothion. The gene encoding the organophosphorus hydrolytic enzyme was cloned and sequenced. The sequence was similar to mpd, a gene previously shown to encode a parathion-methyl-hydrolyzing enzyme in Plesiomonas sp. M6. The inoculation of strain FDS-1 (106 cells g−1) to soil treated with 100 mg fenitrothion emulsion kg−1 resulted in a higher degradation rate than in noninoculated soils regardless of the soil sterilized or nonsterilized. These results highlight the potential of this bacterium to be used in the cleanup of contaminated pesticide waste in the environment.
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    URL: http://dx.doi.org/10.1007/s10532-005-7130-2
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    The Impact of Bioaugmentation on Metal Cyanide Degradation and Soil Bacteria Community Structure (2006)
    Springer
    Biodegradation 17 (2006), S. 207-217 
    Details
    ISSN: 1572-9729
    Keywords: biodegradation ; DGGE ; K2Ni(CN)4 soil bacterial populations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Metal cyanides are significant contaminants of many soils found at the site of former industrial activity. In this study we isolated bacteria capable of degrading ferric ferrocyanide and K2Ni(CN)4. One of these bacteria a Rhodococcus spp. was subsequently used to bioaugment a minimal medium broth, spiked with K2Ni(CN)4, containing 1 g of either an uncontaminated topsoil or a former coke works site soil. Degradation of the K2Ni(CN)4 was observed in both soils, however, bioaugmentation did not significantly impact the rate or degree of K2Ni(CN)4 removal. Statistical analysis of denaturing gradient gel electrophoresis profiles showed that the topsoil bacterial community had a higher biodiversity, and its structure was not significantly affected by either K2Ni(CN)4 or bioaugmentation. In contrast, profiles from the coke works site indicated significant changes in the bacterial community in response to these additions. Moreover, in both soils although bioaugmentation did not affect rates of biodegradation the Rhodococcus spp. did become established in the communities in broths containing both top and coke works soil. We conclude that bacterial communities from contaminated soils with low biodiversity are much more readily perturbed through interventions such as contamination events or bioaugmentation treatments and discuss the implications of these findings for bioremediation studies.
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    URL: http://dx.doi.org/10.1007/s10532-005-4219-6
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    Bioremediation by Composting of Heavy Oil Refinery Sludge in Semiarid Conditions (2006)
    Springer
    Biodegradation 17 (2006), S. 251-261 
    Details
    ISSN: 1572-9729
    Keywords: bioremediation ; composting ; ecotoxicity ; oil sludge
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The present work attempts to ascertain the efficacy of low cost technology (in our case, composting) as a bioremediation technique for reducing the hydrocarbon content of oil refinery sludge with a large total hydrocarbon content (250–300 g kg−1), in semiarid conditions. The oil sludge was produced in a refinery sited in SE Spain The composting system designed, which involved open air piles turned periodically over a period of 3 months, proved to be inexpensive and reliable. The influence on hydrocarbon biodegradation of adding a bulking agent (wood shavings) and inoculation of the composting piles with pig slurry (a liquid organic fertiliser which adds nutrients and microbial biomass to the pile) was also studied. The most difficult part during the composting process was maintaining a suitable level of humidity in the piles. The most effective treatment was the one in which the bulking agent was added, where the initial hydrocarbon content was reduced by 60% in 3 months, compared with the 32% reduction achieved without the bulking agent. The introduction of the organic fertiliser did not significantly improve the degree of hydrocarbon degradation (56% hydrocarbon degraded). The composting process undoubtedly led to the biodegradation of toxic compounds, as was demonstrated by ecotoxicity tests using luminescent bacteria and tests on plants in Petri dishes.
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    URL: http://dx.doi.org/10.1007/s10532-005-5020-2
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    The ACCEL Model for Accelerating the Detoxification Kinetics of Hydrocarbons Requiring Initial Monooxygenation Reactions (2006)
    Springer
    Biodegradation 17 (2006), S. 237-250 
    Details
    ISSN: 1572-9729
    Keywords: activated sludge ; dichlorophenol ; monooxygenation ; nicotinamide adenine dinucleotide ; phenolics ; specific growth rate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The two-tank accelerator/aerator modification of activated sludge significantly increases the biodegradation of hydrocarbons requiring initial monooxygenation reactions, such as phenol and 2,4-dichlorophenol (DCP). The small accelerator tank has a controlled low dissolved oxygen (DO) concentration that can enrich the biomass in NADH + H+. It also has a very high specific growth rate (μacc) that up-regulates the biomass’s content of the monooxygenase enzyme. Here, we develop and test the ACCEL model, which quantifies all key phenomena taking place when the accelerator/aerator system is used to enhance biodegradation of hydrocarbons requiring initial monooxygenations. Monooxygenation kinetics follow a multiplicative relationship in which the organic substrates (phenol or DCP) and DO have separate Monod terms, while the biomass’s content of NADH + H+ has a first-order term. The monooxygenase enzyme has different affinities (K values) for phenol and DCP. The biomass’s NADH + H+ content is based on a proportioning of NAD(H) according to the relative rates of NADH + H+ sources and sinks. Biomass synthesis occurs simultaneously through utilization of acetate, phenol, and DCP, but each has its own true yield. The ACCEL model accurately simulates all trends for one-tank and two-tank experiments in which acetate, phenol, and DCP are biodegraded together. In particular, DCP removal is affected most by DOacc and the retention-time ratio, Θacc/Θtotal. Adding an accelerator tank dramatically increases DCP removal, and the best DCP removal occurs for 0.2 〈 DOacc  〈 0.5 mg/l and 0.08 〈 Θacc/Θtotal 〈 0.2. The rates of phenol and DCP utilization follow the multiplicative relationship with a maximum specific rate coefficient proportional to μacc. Finally, μacc increases rapidly for Θacc/Θtotal 〈 0.25, acetate removal in the accelerator fuels the high μacc, and the biomass’s NADH + H+ content increases very dramatically for DOacc 〈 0.25 mg/l.
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    URL: http://dx.doi.org/10.1007/s10532-005-5019-8
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    Anaerobic Bioremediation of Groundwater Containing a Mixture of 1,1,2,2-Tetrachloroethane and Chloroethenes (2006)
    Springer
    Biodegradation 17 (2006), S. 193-206 
    Details
    ISSN: 1572-9729
    Keywords: bioremediation ; Dehalococcoides ; dechlorination ; microcosm ; tetrachloroethane ; trichloroethene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract This study investigated the biotransformation pathways of 1,1,2,2-tetrachloroethane (1,1,2,2-TeCA) in the presence of chloroethenes (i.e. tetrachloroethene, PCE; trichloroethene, TCE) in anaerobic microcosms constructed with subsurface soil and groundwater from a contaminated site. When amended with yeast extract, lactate, butyrate, or H2 and acetate, 1,1,2,2-TeCA was initially dechlorinated via both hydrogenolysis to 1,1,2-trichloroethane (1,1,2-TCA) (major pathway) and dichloroelimination to dichloroethenes (DCEs) (minor pathway), with both reactions occurring under sulfidogenic conditions. In the presence of only H2, the hydrogenolysis of 1,1,2,2-TeCA to 1,1,2-TCA apparently required the presence of acetate to occur. Once formed, 1,1,2-TCA was degraded predominantly via dichloroelimination to vinyl chloride (VC). Ultimately, chloroethanes were converted to chloroethenes (mainly VC and DCEs) which persisted in the microcosms for very long periods along with PCE and TCE originally present in the groundwater. Hydrogenolysis of chloroethenes occurred only after highly reducing methanogenic conditions were established. However, substantial conversion to ethene (ETH) was observed only in microcosms amended with yeast extract (200 mg/l), suggesting that groundwater lacked some nutritional factors which were likely provided to dechlorinating microorganisms by this complex organic substrate. Bioaugmentation with an H2-utilizing PCE-dechlorinating Dehalococcoides spp. -containing culture resulted in the conversion of 1,1,2,2-TeCA, PCE and TCE to ETH and VC. No chloroethanes accumulated during degradation suggesting that 1,1,2,2-TeCA was degraded through initial dichloroelimination into DCEs and then typical hydrogenolysis into ETH and VC.
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    URL: http://dx.doi.org/10.1007/s10532-005-4218-7
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    Impacts of Bioremediation Schemes on Bacterial Population in Naphthalene-Contaminated Marine Sediments (2006)
    Springer
    Biodegradation 17 (2006), S. 227-235 
    Details
    ISSN: 1572-9729
    Keywords: community fingerprint ; polycyclic aromatic hydrocarbon ; 16S rRNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Microcosm experiments were conduced in which the surface of marine sediment was contaminated with naphthalene and subjected to either of three different bioremediation schemes, i.e., biostimulation (BS) by supplementing with slow-release nitrogen and phosphorus fertilizers, bioaugmentation (BA) by inoculating with Cycloclasticus sp. E2, an aromatics-degrading bacterium identified to play an important role for aromatic-hydrocarbon degradation in marine environments and combination (CB) of BS and BA. These three schemes were found to be similarly effective for removing naphthalene, while naphthalene disappearance in sediment without any treatment (WT) was slower than those in the treated sediments. Shifts in bacterial populations during and after bioremediation were analyzed by denaturing gradient gel electrophoresis (DGGE) of PCR-amplified 16S rRNA gene fragments. It was found that the Cycloclasticus rRNA type occurred as the strongest bands in the course of naphthalene degradation. Clustering analysis of DGGE profiles showed that bacterial populations in the WT, BS and CB sediments differed consistently from those in the uncontaminated control, while the profile for the BA sediment was finally included in the cluster for uncontaminated control sediments after a 150-day treatment. The results suggest that bioaugmentation with ecologically competent pollutant-degrading bacteria is an ecologically promising bioremediation scheme.
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    URL: http://dx.doi.org/10.1007/s10532-005-5018-9
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    Efforts to Explain and Control the Prolonged Thermophilic Period in Two-phase Olive Oil Mill Sludge Composting (2006)
    Springer
    Biodegradation 17 (2006), S. 285-292 
    Details
    ISSN: 1572-9729
    Keywords: composting ; crude oil ; olive mill wastewater ; olive oil mills ; olive tree branches ; olive tree leaves ; sludge ; woodchips
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The aim of this paper was to evaluate the use of different bulking agents in different ratios as a means to control, optimise and eventually reduce the duration of the thermophilic period in two-phase olive oil mill sludge (OOMS) composting. The bulking agents used were: (i) olive tree leaves (OTL), (ii) olive tree shredded branches (OTB) and (iii) woodchips (WDC). The selection of these materials was based on their abundance and availability on the island of Crete, the southernmost point of Greece. The ratios studied were: Pile 1, OOMS:OTL in 1:1 v/v; Pile 2, OOMS:WDC in 1:1.5 v/v; Pile 3, OOMS:OTL in 1:2 v/v; Pile 4, OOMS:OTL:OTB in 1:1:1 v/v; and Pile 5, OOMS:OTL:OTB in 1:1:2 v/v. The composting system used was that of windrows with the volume of each pile approximately 20–25 m3. The experiments took place over two consecutive years. A composting turner was used and turnings were performed at one and two week intervals. In each pile a variety of physiochemical parameters were monitored. Temperature remained high in all five trials. Piles 1, 2, 3, 4 and 5 temperatures recorded values of above 50 °C for 106, 158, 160, 175 and 183 days, respectively. Volumes were reduced by approximately 67%, 62%, 63%, 80% and 84%, respectively. Temperature remained high, mainly due to the presence in large amounts of oily substances which during their complete oxidation release important amounts of energy and aid the cometabolism of more stable molecules such as lignin. This process is better described as the slow “burning” of a “fuel” mixture in an “engine” than composting. This approach is based on the extensive similarities of this process to that of crude oil sludge or similar waste composting.
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    URL: http://dx.doi.org/10.1007/s10532-005-7566-4
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    On kaonic deuterium. Quantum field-theoretic and relativistic covariant approach (2005)
    Springer
    The European physical journal 23 (2005), S. 79-111 
    Details
    ISSN: 1434-601X
    Keywords: 11.10.Ef Lagrangian and Hamiltonian approach ; 11.55.Ds Exact S matrices ; 13.75.Gx Pion-baryon interactions ; 36.10.-k Exotic atoms and molecules (containing mesons, muons, and other unusual particles)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. We study kaonic deuterium, the bound K-d state AK d. Within a quantum field-theoretic and relativistic covariant approach we derive the energy level displacement of the ground state of kaonic deuterium in terms of the amplitude of K-d scattering for arbitrary relative momenta. Near threshold our formula reduces to the well-known DGBT formula. The S-wave amplitude of K-d scattering near threshold is defined by the resonances Λ(1405), Σ(1750) and a smooth elastic background, and the inelastic channels K-d → NY and K-d → NYπ, where Y = Σ±,Σ{0} and Λ{0}, where the final-state interactions play an important role. The Ericson-Weise formula for the S-wave scattering length of K-d scattering is derived. The total width of the energy level of the ground state of kaonic deuterium is estimated using the theoretical predictions of the partial widths of the two-body decays AKd → NY and experimental data on the rates of the NY pair production in the reactions K-d → NY. We obtain Γ{1s} = (630±100)eV. For the shift of the energy level of the ground state of kaonic deuterium we predict ε{1s} = (325±60)eV.
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    The neutron decay retardation spectrometer aSPECT: Electromagnetic design and systematic effects (2005)
    Springer
    The European physical journal 23 (2005), S. 135-146 
    Details
    ISSN: 1434-601X
    Keywords: 23.40.-s Beta decay; double beta decay; electron and muon capture ; 13.30.-a Decays of baryons ; 12.15.Hh Determination of Kobayashi-Maskawa matrix elements
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. The apparatus described here, aSPECT, will be used for a measurement of the neutrino-electron angular correlation coefficient a in the decay of free neutrons. The idea of the aSPECT spectrometer is to measure the integrated proton energy spectrum very accurately using an energy filter by electrostatic retardation and magnetic adiabatic collimation. The main ideas of the spectrometer are presented, followed by an explanation of the adiabatic transmission function. Details of the superconducting coil and of the electrode system are given, as well as a discussion of the most important systematic effects: magnetic field and electrostatic potential inhomogeneities, deviation from adiabatic motion, scattering in the residual gas, background, Doppler effect, edge effect, and detector efficiency. Using this spectrometer, the parameter a is planned to be measured with an absolute experimental uncertainty of δa ≈ 3 . 10-4, from which the axial vector to vector coupling constant ratio λ can be determined with an accuracy of δλ ≈ 0.001.
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    General survey of polarization observables in deuteron electrodisintegration (2005)
    Springer
    The European physical journal 23 (2005), S. 147-190 
    Details
    ISSN: 1434-601X
    Keywords: 21.45.+v Few-body systems ; 24.70.+s Polarization phenomena in reactions ; 25.30.Fj Inelastic electron scattering to continuum ; 13.40.-f Electromagnetic processes and properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. Polarization observables in inclusive and exclusive electrodisintegration of the deuteron using a polarized beam and an oriented target are systematically surveyed using the standard nonrelativistic framework of nuclear theory but with leading-order relativistic contributions included. The structure functions and the asymmetries corresponding to the various nucleon polarization components are studied in a variety of kinematic regions with respect to their sensitivity to realistic NN-potential models, to subnuclear degrees of freedom in terms of meson exchange currents, isobar configurations and to relativistic effects in different kinematical regions, serving as a benchmark for a test of present standard nuclear theory with effective degrees of freedom.
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    From solar proton burning to pionic deuterium through the Nambu-Jona-Lasinio model of light nuclei (2005)
    Springer
    The European physical journal 23 (2005), S. 1-6 
    Details
    ISSN: 1434-601X
    Keywords: 11.10.Ef Lagrangian and Hamiltonian approach ; 13.75.Gx Pion-baryon interactions ; 36.10.-k Exotic atoms and molecules (containing mesons, muons, and other unusual particles) ; 26.65.+t Solar neutrinos
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. Within the Nuclear Nambu-Jona-Lasinio model of light nuclei (the NNJL model), describing strong low-energy nuclear interactions, we compute the width of the energy level of the ground state of pionic deuterium. The theoretical value fits well the experimental data. Using the cross-sections for the reactions νe + d → p + p + e- and νe + d → p + n + νe, computed in the NNJL model, and the experimental values of the events of these reactions, detected by the SNO Collaboration, we compute the boron neutrino fluxes. The theoretical values agree well with the experimental data and the theoretical predictions within the Standard Solar Model by Bahcall. We argue the applicability of the constraints on the astrophysical factor for the solar proton burning, imposed by helioseismology, to the width of the energy level of the ground state of pionic deuterium. We show that the experimental data on the width satisfy these constraints. This testifies an indirect measurement of the recommended value of the astrophysical factor for the solar proton burning in terrestrial laboratories in terms of the width of the energy level of the ground state of pionic deuterium.
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    Search for spontaneous transition of nuclei to a superdense state (2005)
    Springer
    The European physical journal 23 (2005), S. 7-10 
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    ISSN: 1434-601X
    Keywords: 21.10.Ft Charge distribution ; 21.10.-k Properties of nuclei; nuclear energy levels ; 21.65.+f Nuclear matter ; 29.40.Mc Scintillation detectors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. We report the results of an experimental search for spontaneous transition of nuclei from ordinary to superdense state in NaI(Tl). New limits on the superdense-state parameters are presented.
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    Levels in 127La fed by the 127Ce beta-decay (2005)
    Springer
    The European physical journal 23 (2005), S. 33-39 
    Details
    ISSN: 1434-601X
    Keywords: 23.20.Lv γ transitions and level energies ; 27.60.+j 90 ⩽ A ⩽ 149
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. The low-lying levels in 127La have been studied through the β-decay of 127Ce ( T1/2 = 29s) produced by bombarding a natMo target with a 185-MeV 35Cl beam. Reaction products were on-line mass-separated, and γ-ray singles and γ-γ coincidence measurements were performed. Conversion electrons were also measured and multipolarities of transitions have been derived. The half-life of the 210.9-keV level was determined to be (1.9±0.3)ns by the β-γ delayed coincidence technique. The level scheme obtained has been compared with calculations based on the Nilsson model.
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    Coexisting oblate and strongly triaxial structures in 191Pt (2005)
    Springer
    The European physical journal 23 (2005), S. 69-78 
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    ISSN: 1434-601X
    Keywords: 29.30.Kv X- and γ-ray spectroscopy ; 23.20.Lv γ transitions and level energies ; 21.60.Ev Collective models ; 27.80.+w 190 ⩽ A ⩽ 219
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. Excited states in 191Pt have been populated using the reaction 186W + 11B at 85MeV beam energy. Gamma-ray coincidences were measured using the EUROGAM-II spectrometer array. The level scheme has been extended considerably. Evidence for favoured structures of highly triaxial shape with γ ∼ -90° coexisting with oblate structures has been obtained by comparison with total Routhian surface and cranked shell model calculations. The presence of proton excitations in both positive- and negative-parity states has been confirmed.
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    P-wave charmonium decays into baryon and antibaryon pairs in quark pair creation model (2005)
    Springer
    The European physical journal 23 (2005), S. 129-133 
    Details
    ISSN: 1434-601X
    Keywords: 13.25.Gv Decays of J/ψ, ϒ, and other quarkonia ; 12.39.Jh Nonrelativistic quark model ; 14.20.Jn Hyperons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. A simple quark pair creation model is introduced to study exclusive decays of χ{c_J} into baryon-antibaryon pairs. With this simple model, some exclusive decay processes, for example, χ{c0} → B¯ (B = Λ,Σ0,Ξ-) are investigated and their decay widths are evaluated by inclusion of the properties of outgoing baryons, and the results show that the strengthened decay channels χ{c_J} → Λ¯(J = 0, 2) are easily understood by considering only the color singlet contribution of P-wave charmonium.
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    Beta-decay studies of neutron-rich Sc- Cr nuclei (2005)
    Springer
    The European physical journal 23 (2005), S. 41-48 
    Details
    ISSN: 1434-601X
    Keywords: 27.50.+e 59 ⩽ A ⩽ 89 ; 23.40.-s β decay; double β decay; electron and muon capture ; 21.60.Cs Shell model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. The neutron-rich nuclei          2157, 58Sc,          2258-60Ti,          2360-63V,          2462-66Cr have been produced at Ganil via interactions of a 61.8A MeV 76Ge beam with a 58Ni target. Beta-decay studies have been performed using combined β- and γ-ray spectroscopy. Half-lives have been determined and β-decay schemes are proposed for 58Ti, 61V and 62Cr. From these studies, new hints for the existence of β-decaying isomers in 60V and in 62Mn are provided. These results are compared to shell model calculations. The role of the πf7/2- νf5/2 proton-neutron interaction is examined through its influence on the lifetime values.
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    Spallation neutron spectrum on a massive lead/paraffin target irradiated with 1 GeV protons (2005)
    Springer
    The European physical journal 23 (2005), S. 61-68 
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    ISSN: 1434-601X
    Keywords: 28.41.Kw Radioactive wastes, waste disposal ; 29.30.Kv X- and γ-ray spectroscopy ; 02.70.Uu Applications of Monte Carlo methods ; 07.05.Fb Design of experiments
    Source: Springer Online Journal Archives 1860-2000
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    Notes: Abstract. The gamma-ray spectra emitted by decaying of residual nuclei produced by spallation neutrons in (n, xn), (n, xnyp), (n, p), (n, γ) reactions with activation threshold detectors, i.e. 209Bi, 197Au, 59Co, 115In, 232Th, were measured in the Laboratory of Nuclear Problems (LNP), JINR, Dubna, Russia. Spallation neutrons were generated by bombarding a 20 cm long cylindrical lead target with 8 cm diameter surrounded by a 6 cm thick layer of paraffin moderator with 1 GeV proton beam from the NUCLOTRON accelerator. Reaction rates and a spallation neutron spectrum were measured and compared with CASCADE code calculations.
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    Emission of unbound 8Be and 12C * (0+2) clusters in compound nucleus reactions (2005)
    Springer
    The European physical journal 23 (2005), S. 19-31 
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    ISSN: 1434-601X
    Keywords: 21.60.Gx Cluster models ; 23.90.+w Other topics in radioactive decay and in-beam spectroscopy ; 25.70.Gh Compound nucleus ; 25.70.Pq Multifragment emission and correlations
    Source: Springer Online Journal Archives 1860-2000
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    Notes: Abstract. We have studied the emission of light unbound clusters, 8Be and 12C * (0+2), in the reactions 18O + 13C →{31} Si →{23} Ne + 8Be and 28Si + 24Mg →{52} Fe →{40} Ca + 12C * (0+2). The γ-ray spectra obtained in coincidence with 8Be and 12C * (0+2) emission have been studied relative to the statistical emission of two or three α-particles. The angular-momentum-to-energy balance of the cluster emission is compared with that of multiple-α emission. The properties of the energy spectra of the binary process and the population of the residual nuclei by cluster emission are discussed. It is observed that cluster emission carries away less excitation energy on average than the sequential emission of the individual components.
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    Quark-meson SU(3) model in a Tamm-Dancoff inspired approximation (2005)
    Springer
    The European physical journal 38 (2005), S. 483-494 
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    Notes: Abstract. The non-linear chiral quark-meson U(3) x U(3) model is solved using the Tamm-Dancoff inspired approximation which is described in an earlier paper [Phys. Rev. D 58, 034003 (1998)]. The resulting system of 15 coupled non-linear differential equations self-consistently determines all quark-meson coupling constants. Also the obtained solutions for quark and meson fields are stable and physically acceptable. As the zeroth approximation of a more refined structure they were used to calculate SU(3) baryon octet magnetic moments and axial coupling constants with baryon state vectors containing valence quarks only, at this primordial level. The results are very promising, so possibilities to pursuit more sophistication and improved physical input is indicated.
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    Diffractive $\gamma \gamma$ production at hadron colliders (2005)
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    The European physical journal 38 (2005), S. 475-482 
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    Notes: Abstract. We compute the cross section for exclusive double-diffractive $\gamma \gamma$ production at the Tevatron, $p{\bar{p}} \to p + \gamma \gamma + {\bar{p}}$ , and the LHC. We evaluate both the gg and $q\bar{q}\;\; t$ -channel exchange contributions to the process. The observation of exclusive $\gamma \gamma$ production at the Tevatron will provide a check on the model predictions and offer an opportunity to confirm the expectations for exclusive double-diffractive Higgs production at the LHC.
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    Measurement of the energy dependence of hadronic jet rates and the strong coupling $\alpha_s$ from the four-jet rate with the DELPHI detector at LEP (2005)
    Springer
    The European physical journal 38 (2005), S. 413-426 
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    Notes: Abstract. Hadronic events from the data collected with the DELPHI detector at LEP within the energy range from 89 Gev to 209 Gev are selected, their jet rates are determined and compared to predictions of four different event generators. One of them is the recently developed APACIC + + generator which performs a massive matrix element calculation matched to a parton shower followed by string fragmentation. The four-jet rate is used to measure $\alpha_s$ in the next-to-leading-order approximation yielding $${\alpha_s(M_Z^2)} = 0.1175 \pm 0.0030. $$ The running of $\alpha_s$ determined by using four-jet events has been tested. The logarithmic energy slope is measured to be $$ \frac{{\mathrm{d}}\alpha_s^{-1}}{{\mathrm{d}} \log E_{\mathrm {cm}}} = 1.14 \pm 0.36. $$ Since the analysis is based on four-jet final states it represents an alternative approach to previous DELPHI $\alpha_s$ measurements using event shape distributions.
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    Zero-curvature formalism of supersymmetric principal chiral model (2005)
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    The European physical journal 38 (2005), S. 521-526 
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    Notes: Abstract. We investigate the one-parameter family of transformations on superfields of the super principal chiral model and obtain different zero-curvature representations of the model. The parametric transformation is related to the super Riccati equations and an infinite set of local and non-local conservation laws is derived. A Lax representation of the model is presented which gives rise to a superspace monodromy operator.
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    Leading-particle suppression in high energy nucleus-nucleus collisions (2005)
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    The European physical journal 38 (2005), S. 461-474 
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    Notes: Abstract. Parton energy loss effects in heavy-ion collisions are studied with the Monte Carlo program PQM (Parton Quenching Model) constructed using the BDMPS quenching weights and a realistic collision geometry. The merit of the approach is that it contains only one free parameter that is tuned to the high-p t nuclear modification factor measured in central Au-Au collisions at $\sqrt{s_{\rm NN}} = 200$ GeV. Once tuned, the model is consistently applied to all the high-p t observables at 200 GeV: the centrality evolution of the nuclear modification factor, the suppression of the away-side jet-like correlations, and the azimuthal anisotropies for these observables. Predictions for the leading-particle suppression at nucleon-nucleon centre-of-mass energies of 62.4 and 5500 GeV are presented. The limits of the eikonal approximation in the BDMPS approach, when applied to finite-energy partons, are discussed.
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    Modeling the pion and kaon form factors in the timelike region (2005)
    Springer
    The European physical journal 39 (2005), S. 41-54 
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    Topics: Physics
    Notes: Abstract. New, accurate measurements of the pion and kaon electromagnetic form factors are expected in the near future from experiments at electron-positron colliders, using the radiative return method. We construct a model for the timelike pion electromagnetic form factor that is valid also at momentum transfers far above the $\rho$ resonance. The ansatz is based on vector dominance and includes a pattern of radial excitations expected from dual resonance models. The form factor is fitted to the existing data in the timelike region, continued to the spacelike region and compared with the measurements there and with the QCD predictions. Furthermore, the model is extended to the kaon electromagnetic form factor. Using isospin and SU(3)-flavor symmetry relations we extract the isospin-one contribution and predict the kaon weak form factor accessible in semileptonic $\tau$ decays.
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    On the boundary conditions as Dirac constraints (2005)
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    The European physical journal 39 (2005), S. 123-127 
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    Notes: Abstract. In this paper, the canonical quantization of singular Lagrangian defined in a finite volume is discussed by studying a 1 + 1 dimensional free Schrödinger field. We take the boundary conditions (BCs) as Dirac constraints, and show that those BCs as well as the intrinsic constraints (which are introduced by the singularities of Lagrangian) form the second class constraints. The quantization is performed canonically.
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    The low-lying mass spectrum of the N = 1 SU(2) SUSY Yang-Mills theory with Wilson fermions (2005)
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    The European physical journal 39 (2005), S. 87-94 
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    Notes: Abstract. We analyze the low energy spectrum of bound states of the N = 1 SU(2) SUSY Yang-Mills Theory (SYM). This work continues the investigation of the non-perturbative properties of SYM by Monte Carlo simulations in the Wilson discretization with dynamical gluinos. The dynamics of the gluinos is included by the Two-Step Multi-Bosonic Algorithm (TSMB) for dynamical fermions. A new set of configurations has been generated on a $16^3\cdot 32$ lattice at $\beta = 2.3$ and $\kappa = 0.194$ . The analysis also includes sets of configurations previously generated on a smaller ( $12^3\cdot 24$ ) lattice at $\kappa = 0.1925, 0.194$ and 0.1955. Guided by predictions from low energy Lagrangians, we consider spin-1/2, scalar and pseudoscalar particles. The spectrum of SYM is a challenging subject of investigation because of the extremely noisy correlators. In particular, meson-like correlators contain disconnected contributions. The larger time-extension of the $16^3\cdot 32$ lattice allows to observe two-state signals in the effective mass. Finite-volume effects are monitored by comparing results from the two lattice sizes.
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    Split supersymmetry at colliders (2005)
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    The European physical journal 39 (2005), S. 229-243 
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    Notes: Abstract. We consider the collider phenomenology of split-supersymmetry models. Despite the challenging nature of the signals in these models the long-lived gluino can be discovered with masses above 2 TeV at the LHC. At a future linear collider we will be able to observe the renormalization group effects from split supersymmetry, using measurements of the neutralino and chargino masses and cross sections.
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    Comments on spin operators and spin-polarization states of 2 + 1 fermions (2005)
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    The European physical journal 39 (2005), S. 245-248 
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    Notes: Abstract. In this brief article we discuss spin-polarization operators and spin-polarization states of 2 + 1 massive Dirac fermions and find a convenient representation by the help of 4-spinors for their description. We stress that in particular the use of such a representation allows us to introduce the conserved covariant spin operator in the 2 + 1 field theory. Another advantage of this representation is related to the pseudoclassical limit of the theory. Indeed, quantization of the pseudoclassical model of a spinning particle in 2 + 1 dimensions leads to the 4-spinor representation as the adequate realization of the operator algebra, where the corresponding operator of a first-class constraint, which cannot be gauged out by imposing the gauge condition, is just the covariant operator previously introduced in the quantum theory.
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    Nuclear parton distribution functions and energy-loss effect in the Drell-Yan reaction off nuclei (2005)
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    The European physical journal 39 (2005), S. 179-184 
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    Notes: Abstract. The energy-loss effect in nuclear matter is another nuclear effect apart from the nuclear effects on the parton distribution as in deep inelastic scattering process. The quark energy loss can be measured best by the nuclear dependence of the high energy nuclear Drell-Yan process. By means of two typical kinds of quark energy-loss parametrization and the different sets of nuclear parton distribution functions, we present an analysis of the E866 experiments on the nuclear dependence of Drell-Yan lepton pair production resulting from the bombardment of Be, Fe and W targets by 800 GeV protons at Fermilab. It is found that the quark energy loss in cold nuclei is strongly dependent on the used nuclear parton distribution functions. The further prospects of using relatively low energy protons incident on nuclear targets are presented by combining the quark energy-loss rate determined from a fit to the E866 nuclear-dependent ratios versus x 1, with the nuclear parton distribution functions given from lA deep inelastic scattering (DIS) data. The experimental study of the relatively low energy nuclear Drell-Yan process can give valuable insight in the energy loss of the fast quark propagating through cold nuclei and help to pin down nuclear parton distribution functions.
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    Spectrum of recoil nucleons in quasi-elastic neutrino-nucleus interactions (2005)
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    The European physical journal 39 (2005), S. 195-200 
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    Notes: Abstract. We have analyzed the consequences of introducing the local density approximation combined with an effective nuclear momentum-dependent potential into the CC quasi-elastic neutrino-nucleus scattering. We note that the distribution of recoil nucleons momenta becomes smooth for low momentum values and the sharp threshold is removed. Our results may be relevant for Sci-Fi detector analysis of K2K experiments. The total amount of observed recoil protons is reduced because some of them remain bound inside the nucleus. We compare theoretical predictions for a probability of such events with the results given by NUX + FLUKA MC simulations.
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    Effective action and Hawking flux from covariant perturbation theory (2005)
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    The European physical journal 40 (2005), S. 275-286 
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    Notes: Abstract. The computation of the radiation flux related to the Hawking temperature of a Schwarzschild black hole or another geometric background is still well-known to be fraught with a number of delicate problems. In spherical reduction, as shown by one of the present authors (Kummer) with Vassilevich, the correct black body radiation follows when two “basic components” (conformal anomaly and a “dilaton” anomaly) are used as input in the integrated energy-momentum conservation equation. The main new element in the present work is the use of a quite different method, the covariant perturbation theory of Barvinsky and Vilkovisky, to establish directly the full effective action which determines these basic components. In the derivation of Kummer and Vassilevich the computation of the dilaton anomaly implied one potentially doubtful intermediate step which can be avoided here. Moreover, the present approach also is sensitive to IR (renormalization) effects. We realize that the effective action naturally leads to expectation values in the Boulware vacuum which, making use of the conservation equation, suffice for the computation of the Hawking flux in other quantum states, in particular for the relevant Unruh state. Thus, a rather comprehensive discussion of the effects of (UV and IR) renormalization upon radiation flux and energy density is possible.
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    New gauge bosons from the littlest Higgs modeland the process $e^{ + }e^{-}\rightarrow t\bar{t}$ (2005)
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    The European physical journal 40 (2005), S. 251-258 
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    Notes: Abstract. In the context of the littlest Higgs (LH) model, we study the process $e^{ + }e^{-}\rightarrow t\bar{t}$ . We find that the new gauge bosons Z H and B H can produce significant correction effects on this process, which can be further enhanced by suitably polarized beams. In most of the parameter space preferred by the electroweak precision data, the absolute value of the relative correction parameter $R_{B_{H}}$ is larger than 5 %. As long as $1 {\mathrm {TeV}} \leq M_{Z_{H}}\leq 1.5 {\mathrm {TeV}} $ and $0.3\leq c\leq 0.5,$ the absolute value of the relative correction parameter $R_{Z_{H}}$ is larger than $5\%$ . With reasonable values of the parameters of the LH model, the possible signals of the new gauge bosons B H and Z H can be detected via the process $e^{ + }e^{-}\rightarrow t\bar{t}$ in the future LC experiments with the CM energy $\sqrt{S} = 800 {\mathrm {GeV}} $ . B H exchange and Z H exchange can generate significantly corrections to the forward-backward asymmetry $A_{\mathrm {{FB}}}(t\bar{t})$ only in a small part of the parameter space.
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    Measurement of event shape distributions and moments in e + e $^-\rightarrow \mathrm{hadrons}$ at 91-209 GeV and a determination of $\ensuremath{\alpha_{\mathrm{s}}}$ (2005)
    Springer
    The European physical journal 40 (2005), S. 287-316 
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    Notes: Abstract. We have studied hadronic events from e + e- annihilation data at centre-of-mass energies from 91 to 209 GeV. We present distributions of event shape observables and their moments at each energy and compare with QCD Monte Carlo models. From the event shape distributions we extract the strong coupling $\ensuremath{\alpha_{\mathrm{s}}}$ and test its evolution with energy scale. The results are consistent with the running of $\ensuremath{\alpha_{\mathrm{s}}}$ expected from QCD. Combining all data, the value of $\ensuremath{\alpha_{\mathrm{s}}} \ensuremath{(M_{\mathrm{Z}})}$ is determined to be $$ \ensuremath{\alpha_{\mathrm{s}}}\ensuremath{M_{\mathrm{Z}}} = 0.1191 \pm0.0005 \mathrm{(stat.)} \pm0.0010\mathrm{(expt.)} \pm0.0011 \mathrm{(hadr.)} \pm0.0044 \mathrm{(theo.)}\,. $$ The energy evolution of the moments is also used to determine a value of $\ensuremath{\alpha_{\mathrm{s}}}$ with slightly larger errors: $\ensuremath{\alpha_{\mathrm{s}}} \ensuremath{M_{\mathrm{Z}}}=0.1223\pm 0.0005(\mathrm{stat.})\pm 0.0014(\mathrm{expt.})\pm 0.0016(\mathrm{hadr.})^{+0.0054}_{-0.0036}(\mathrm{theo.})$ .
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    Study of spin and decay-plane correlations of W bosons in the e + e $^-\rightarrow$ W + W- process at LEP (2005)
    Springer
    The European physical journal 40 (2005), S. 333-341 
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    Notes: Abstract. Data collected at LEP at centre-of-mass energies $\sqrt{s} = 189-209$ GeV are used to study correlations of the spin of W bosons using $\mathrm{e}^ + \mathrm{e}^-\to \mathrm{W}^ + \mathrm{W}^-\to {\ensuremath{\ell\nu\mathrm{q\bar{q}}}}$ events. Spin correlations are favoured by data, and found to agree with the Standard Model predictions. In addition, correlations between the W-boson decay planes are studied in $\mathrm{e}^ + \mathrm{e}^-{}\to{}\mathrm{W}^ + \mathrm{W}^- \to{}{\ensuremath{\ell\nu\mathrm{q\bar{q}}}}$ and $\mathrm{e}^ + \mathrm{e}^-{}\to{}\mathrm{W}^ + \mathrm{W}^-{}\to{}{\ensuremath{\text{q}\bar{\text{q}}\text{q}\bar{\text{q}}}}{}$ events. Decay-plane correlations are measured to be consistent with the Standard Model predictions.
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    Measurements of the charge asymmetry of the Dalitz plot parameters for $K^{\pm}\to\pi^{\pm}\pi^0\pi^0$ decays (2005)
    Springer
    The European physical journal 40 (2005), S. 343-347 
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    Notes: Abstract. The charge asymmetry of the g, h, and k Dalitz plot parameters for ${K^{\pm}\rightarrow \pi^{\pm} \pi^{0} \pi^{0}}$ decays has been measured with 35 GeV/c hadron beams at the 70 GeV IHEP accelerator. The g, h, and k values obtained appear to be identical for $K^{\pm}$ decays within the errors quoted. In particular, the charge asymmetry A g = (g + – g -)/(g + + g -) of the slope g is equal to ${(0.2 \pm 1.9)\cdot 10^{-3}}$ .
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    Measurement of $F_2^{c\bar{c}}$ and $F_2^{b\bar{b}}$ at high Q 2 using the H1 vertex detector at HERA (2005)
    Springer
    The European physical journal 40 (2005), S. 349-359 
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    Notes: Abstract. Measurements are presented of inclusive charm and beauty cross sections in e + p collisions at HERA for values of photon virtuality Q 2 〉 150 GeV2 and of inelasticity 0.1 〈 y 〈 0.7. The charm and beauty fractions are determined using a method based on the impact parameter, in the transverse plane, of tracks to the primary vertex, as measured by the H1 vertex detector. The data are divided into four regions in Q 2 and Bjorken x, and values for the structure functions $F_2^{c\bar{c}}$ and $F_2^{b\bar{b}}$ are obtained. The results are found to be compatible with the predictions of perturbative quantum chromodynamics.
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    New method to extract the neutron-electron scattering length (2005)
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    The European physical journal 40 (2005), S. 473-477 
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    Notes: Abstract. A novel method to extract the neutron-electron scattering length b ne from the precise neutron scattering data measured for a noble gas at several different densities n is proposed. The main point of this method is dividing the experimental data into two parts: the first, nearly proportional to n, corresponding to diffraction on neighboring atoms and the second one, a small contribution of n, e scattering independent on n. The proposed technique is demonstrated using the structure factor S(q) for gaseous krypton.
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    Polarized forward-backward asymmetries of leptonsin $B_s \rightarrow \ell^ + \ell^- \gamma$ decay (2005)
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    The European physical journal 40 (2005), S. 505-514 
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    Notes: Abstract. Polarized forward-backward asymmetries in the $B_s \rightarrow \ell^ + \ell^- \gamma$ decay are calculated using the most general, model independent form of the effective Hamiltonian, including all possible forms of interactions. The dependencies of the asymmetries on new Wilson coefficients are investigated. The detectability of the asymmetries at LHC is discussed.
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    Neutrino dimuon production and the strangeness asymmetry of the nucleon (2005)
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    The European physical journal 40 (2005), S. 145-156 
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    Notes: Abstract. We have performed the first global QCD analysis to include the CCFR and NuTeV dimuon data, which provide direct constraints on the strange and antistrange parton distributions, s(x) and $\bar{s}(x)$ . To explore the strangeness sector, we adopt a general parametrization of the non-perturbative $s(x), \bar{s}(x)$ functions satisfying basic QCD requirements. We find that the strangeness asymmetry, as represented by the momentum integral $[S^{-}]\equiv \int_0^1 x [s(x)-\bar{s}(x)] \mathrm dx$ , is sensitive to the dimuon data provided the theoretical QCD constraints are enforced. We use the Lagrange multiplier method to probe the quality of the global fit as a function of [S -] and find -0.001 〈 [S -] 〈 0.004. Representative parton distribution sets spanning this range are given. Comparisons with previous work are made.
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    Correlator of heavy-quark currents at small q 2 in the large- $\beta_0$ limit (2005)
    Springer
    The European physical journal 40 (2005), S. 157-164 
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    Notes: Abstract. The correlator of vector heavy-quark currents at small q 2 is considered in the large- $\beta_0$ limit. The leading IR renormalon ambiguity of the sum of the perturbative series is canceled by the UV renormalon ambiguity of the gluon condensate. The asymptotic behavior of the perturbative series is obtained in a model-independent way, up to a single unknown normalization factor. Gluon-virtuality distribution functions for the perturbative correction are calculated.
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    URL: http://dx.doi.org/10.1140/epjc/s2005-02124-2
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    Analyses of k t distributions at RHIC by means of some selected statistical and stochastic models (2005)
    Springer
    The European physical journal 40 (2005), S. 243-250 
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    Notes: Abstract. The new data on k t distributions obtained at RHIC are analyzed by means of selected models of statistical and stochastic origin in order to estimate their importance in providing new information on the hadronization process, in particular on the value of the temperature at freeze-out to the hadronic phase.
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    A flavor symmetry for quasi-degenerate neutrinos: $L_\mu - L_\tau$ (2005)
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    The European physical journal 40 (2005), S. 259-268 
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    Notes: Abstract. We consider the flavor symmetry $L_\mu - L_\tau$ for the neutrino mass matrix. The most general neutrino mass matrix conserving $L_\mu - L_\tau$ predicts quasi-degenerate neutrino masses with one maximal and two zero mixing angles. The presence of $L_\mu - L_\tau$ can also be motivated by the near-bimaximal form of the neutrino mixing matrix. Furthermore, it is a special case of $\mu \tau$ symmetric mass matrices. Breaking the flavor symmetry by adding a small flavor-blind term to the neutrino mass matrix and/or by applying radiative corrections is shown to reproduce the observed neutrino oscillation phenomenology. Both the normal and inverted mass ordering can be accommodated within this scheme. Moderate cancellation for neutrinoless double beta decay is expected. The observables |U e3|2 and $\vert 1/2 - \sin^2\theta_{23}\vert$ are proportional to the inverse of the fourth power of the common neutrino mass scale. We comment on whether the atmospheric neutrino mixing is expected to lie above or below $\pi/4$ . We finally present a model based on the see-saw mechanism which generates a light neutrino mass matrix with an (approximate) $L_\mu - L_\tau$ flavor symmetry. This is a minimal model with just one standard Higgs doublet and three heavy right-handed neutrinos. It needs only small values for the soft $L_\mu - L_\tau$ breaking terms to reproduce the phenomenological viable mass textures analyzed.
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    The difference between n-dimensional regularization and n-dimensional reduction in QCD (2005)
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    The European physical journal 40 (2005), S. 199-203 
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    Notes: Abstract. We discuss the difference between n-dimensional regularization and n-dimensional reduction for processes in QCD which have an additional mass scale. Examples are heavy flavor production in hadron-hadron collisions or on-shell photon-hadron collisions where the scale is represented by the mass m. Another example is electroproduction of heavy flavors where we have two mass scales given by m and the virtuality of the photon $\smash[b]{Q = \sqrt{-q^2}}$ . Finally we study the Drell-Yan process where the additional scale is represented by the virtuality $\smash[t]{Q = \sqrt{q^2}}$ of the vector boson ( $\gamma^*, W, Z$ ). The difference between the two schemes is not accounted for by the usual oversubtractions. There are extra counter terms which multiply the mass scale dependent parts of the Born cross sections. In the case of the Drell-Yan process it turns out that the off-shell mass regularization agrees with n-dimensional regularization.
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    Renormalization-group improved calculation of the $B\to X_s\gamma$ branching ratio (2005)
    Springer
    The European physical journal 40 (2005), S. 165-186 
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    Notes: Abstract. Using results on soft-collinear factorization for inclusive B-meson decay distributions, a systematic study of the partial $B\to X_s\gamma$ decay rate with a cut $E_\gamma\ge E_0$ on photon energy is performed. For values of E 0 below about 1.9 GeV, the rate can be calculated without reference to shape functions using a multi-scale operator product expansion (MSOPE). The transition from the shape-function region to the MSOPE region is studied analytically. The resulting prediction for the $B\to X_s\gamma$ branching ratio depends on three large scales: m b , $\sqrt{m_b\Delta}$ , and $\Delta = m_b-2E_0$ . Logarithms associated with these scales are resummed at next-to-next-to-leading logarithmic order. While power corrections in $\Lambda_{\mathrm {QCD}}/\Delta$ turn out to be small, the sensitivity to the scale $\Delta\approx 1.1$ GeV (for $E_0\approx 1.8$ GeV) introduces significant perturbative uncertainties, which so far have been ignored. The new theoretical prediction for the $B\to X_s\gamma$ branching ratio with $E_\gamma\ge 1.8$ GeV is $\mbox{Br}(B\to X_s\gamma) = \smash{(3.38_{ -0.42}^{ + 0.31}\pm 0.31)}\times 10^{-4}$ , where the first error is an estimate of perturbative uncertainties and the second one reflects uncertainties in input parameters. With this cut $\smash{(89_{ -7}^{ + 6} \pm 1)}\%$ of all events are contained. When this fraction is combined with the previously best prediction for the total decay rate, one obtains $\mbox{Br}(B\to X_s\gamma) = (3.30_{ -0.35}^{ + 0.31}\pm 0.17)\times 10^{-4}$ , with a somewhat less conservative estimate of parametric uncertainties. The implications of larger theory uncertainties for new physics searches are briefly explored with the example of the type-II two-Higgs-doublet model, for which the lower bound on the charged-Higgs mass is reduced compared with previous estimates to approximately 200 GeV at 95% confidence level.
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    Two-parton twist-3 factorization in perturbative QCD (2005)
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    The European physical journal 40 (2005), S. 395-417 
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    Notes: Abstract. We prove the collinear factorization theorem for the process $\pi\gamma^*\to\pi$ at the twist-3 level in the covariant gauge by means of the Ward identity, concentrating on the two-parton case. It is shown that soft divergences cancel and collinear divergences are grouped into the pseudo-scalar and pseudo-tensor two-parton twist-3 pion distribution amplitudes. The delicate summation of a complete set of diagrams for achieving factorization in momentum, spin, and color spaces is emphasized. The proof is then extended to the exclusive semileptonic decay $B\to\pi l\nu$ , assuming the hard scale to be of $O\smash{\bigl(\sqrt{\bar{\Lambda} M_B}\bigr)}$ , where $\bar{\Lambda}$ is a hadronic scale and M B the B meson mass. We explain the distinction between the factorization of collinear divergences for a pion distribution amplitude and of soft divergences for a B meson distribution amplitude. The gauge invariance and universality of the two-parton twist-3 pion distribution amplitudes are confirmed. The proof presented here can accommodate the leading twist-2 case. We then compare our proof with that performed in the framework of soft-collinear effective theory.
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    Exclusive semileptonic rare decays $B \to K^{(*)} l^ + l^-$ in a SUSY SO(10) GUT (2005)
    Springer
    The European physical journal 40 (2005), S. 565-577 
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    Notes: Abstract. In the SUSY SO(10) GUT context, we study the exclusive processes $B \to K^{(*)} l^ + l^-(l = \mu,\tau)$ . Using the Wilson coefficients of the relevant operators including the new operators $\smash{Q_{1,2}^{(\prime)}}$ which are induced by neutral Higgs boson (NHB) penguins, we evaluate some possible observables associated with these processes like the invariant mass spectrum (IMS), lepton pair forward-backward asymmetry (FBA), lepton polarization asymmetries etc. In this model the contributions from Wilson coefficients $C_{Q_{1,2}}^\prime$ , among new contributions, are dominant. Our results show that the NHB effects are sensitive to the FBA, $\mathrm {d}L/\mathrm {d}\hat{s}$ , and $\mathrm {d}T/\mathrm {d}\hat{s}$ of $B \to K^{(*)} \tau^ + \tau^-$ decay, which are expected to be measured in B factories, the deviation of $\mathrm {d}T/\mathrm {d}\hat{s}$ in $B \to K \mu^ + \mu^-$ can reach 0.1 from SM, which could be seen in B factories, and the average of the normal polarization $\mathrm {d}N/\mathrm {d}\hat{s}$ can reach several percent for $B \to K \mu^ + \mu^-$ and it is 0.05 or so for $B\to K \tau^ + \tau^-$ , which could be measured in the future super B factories and provide useful information to probe new physics and discriminate different models.
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    Final results from phase II of the Mainz neutrino mass searchin tritium ${\beta}$ decay (2005)
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    The European physical journal 40 (2005), S. 447-468 
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    Notes: Abstract. This paper reports on the improved Mainz experiment on tritium $\beta$ spectroscopy which yields a 10 times higher signal to background ratio than before. The main experimental effects and systematic uncertainties have been investigated in side experiments, and possible error sources have been eliminated. Extensive data taking took place in the years 1997 to 2001. A residual analysis of the data sets yields for the square of the electron antineutrino mass the final result of $m^2(\nu_e) = (-0.6 \pm 2.2_{\mathrm{{stat}}} \pm 2.1_{\mathrm{{syst}}})$ eV2/c4. We derive an upper limit of $m(\nu_e)\leq 2.3$ eV/c2 at 95% confidence level for the mass itself.
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    Corrections to quark asymmetries at LEP (2005)
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    The European physical journal 40 (2005), S. 493-496 
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    Notes: Abstract. The most precise measurement of the weak mixing angle $\sin^2 \theta_{\mathrm{eff}}^l$ at LEP is from the forward-backward asymmetry $e^ + e^- \rightarrow b \overline{b}$ at the Z-pole. In this note the QED and electroweak radiative corrections to obtain the pole asymmetry from the measured asymmetry for b- and c-quarks have been calculated using ZFITTER, which has been amended to allow a consistent treatment of partial two-loop corrections for the b-quark final asymmetries. A total correction of $\delta A_{\mathrm{FB}}^{{b}} = 0.0019 \pm 0.0002$ and $\delta A_{\mathrm{FB}}^{{c}} = 0.0064 \pm 0.0001$ has been found, where the remaining theoretical uncertainty is much too small to explain the apparent discrepancy between $\sin^2 \theta_{\mathrm{eff}}^l$ obtained from A FB b and from the left-right asymmetry at SLD.
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    Probing the perturbative NLO parton evolution in the small-x region (2005)
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    The European physical journal 40 (2005), S. 515-517 
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    Notes: Abstract. A dedicated test of the perturbative QCD NLO parton evolution in the very small-x region is performed. We find a good agreement with recent precision HERA data for F 2 p(x,Q 2), as well as with the present determination of the curvature of F 2 p. Characteristically, perturbative QCD evolutions result in a positive curvature which increases as x decreases. Future precision measurements in the very small x-region, x 〈 10-4, could provide a sensitive test of the range of validity of perturbative QCD.
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    On voltage-current characteristics and critical current in Bi-2212 (2005)
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    The European physical journal 43 (2005), S. 39-45 
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    Notes: Abstract. V(I) characteristics have been performed in a monocrystalline microbridge of Bi[ Pb $]-2212$ . The vortex phase diagram has been greatly investigated. Linear but non-ohmic Voltage (Current) (V(I)) curves with a well defined critical current have been observed. A departure from this behavior is observed near the peak effect where an out of equilibrium high threshold current can be stabilized. At high temperature, the critical current persists in the “liquid” state despite the dissipation at the lowest bias. Some implications of these results are discussed. In particular, it is proposed that the surface disorder, rather than the bulk disorder, is responsible for the vortex pinning in this sample.
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    Electronic structure of the Sr0.4Ca13.6Cu24O41 incommensurate compound (2005)
    Springer
    The European physical journal 43 (2005), S. 29-37 
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    Notes: Abstract. We extracted, from strongly-correlated ab-initio calculations, a complete model for the chain subsystem of the Sr0.4Ca13.6Cu24O41 incommensurate compound. A second neighbor t-J+V model has been determined as a function of the fourth crystallographic parameter τ, for both low and room temperature crystallographic structures. The analysis of the obtained model shows the crucial importance of the structural modulations on the electronic structure through the on-site energies and the magnetic interactions. The structural distortions are characterized by their long range effect on the cited parameters that hinder the reliability of analyses such as BVS. One of the most striking results is the existence of antiferromagnetic nearest-neighbor interactions for metal-ligand-metal angles of 90○. A detailed analysis of the electron localization and spin arrangement is presented as a function of the chain to ladder hole transfer and of the temperature. The obtained spin arrangement is in agreement with antiferromagnetic correlations in the chain direction at low temperature.
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    Generic two-phase coexistence in nonequilibrium systems (2005)
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    The European physical journal 43 (2005), S. 73-79 
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    Notes: Abstract. A beautifully simple model introduced a couple of decades ago, Toom’s cellular automaton, revealed that non-equilibrium systems may exhibit generic bistability, i.e. two-phase coexistence over a finite area of the (two-dimensional) phase diagram, in violation of the equilibrium Gibbs phase rule. In this paper we analyse two interfacial models, describing more realistic situations, that share with Toom’s model a phase diagram with a broad region of phase coexistence. An analysis of the interfacial models yields conditions for generic bistability in terms of physically relevant parameters that may be controlled experimentally.
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    Uncompensated antiferromagnetic structure of Ho2Ni2Pb (2005)
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    The European physical journal 43 (2005), S. 163-174 
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    Notes: Abstract. We have studied the magnetic structure of the orthorhombic compound Ho2Ni2Pb by means of neutron diffraction in zero field and in magnetic fields up to 4.5 T. Both powder and single-crystalline samples were used. Previous bulk measurements suggest two distinct magnetic phase transitions: one at TN = 7.0 K and the other at 4.8 K. Our neutron diffraction measurements, which were made in the range 1.5-20 K, showed that Ho2Ni2Pb has a collinear magnetic structure with unequal number of up and down Ho moments that are aligned parallel and antiparallel to the c axis. At the lowest temperatures the Ho moments are equal in size, each 8.3 μB in agreement with magnetization data. The magnetic structure can be described as having a 5a ×b ×c magnetic unit cell. Below Ts = 3.0 K the structure is squared up. A smooth development of all the magnetic moment magnitudes indicates that the magnetic structure remains in principle the same over the whole temperature range, the “phase transition” around 4.8 K can be identified as an inflection point in the temperature dependence of one of the Ho moments. With increasing temperature there is a clear development towards a simple transverse sine-wave modulated magnetic structure that is established just below TN.
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    HSSH-model of Hole transfer in DNA (2005)
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    The European physical journal 43 (2005), S. 279-281 
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    Notes: Abstract. A method based on a selfconsistent solution of a quantum-mechanical system with temperature fluctuations described by Langevin equations is developed to calculate the charge carrier mobility in DNA. To model the charge transfer in DNA, a combined Holstein – SSH Hamiltonian is considered. As an example the hole mobility is calculated at room temperature for synthetic poly (G)/poly (C) duplex with regard to main structural fluctuations.
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    Dispersion of incoherent spectral features in systems with strong electron-phonon coupling (2005)
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    The European physical journal 43 (2005), S. 11-18 
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    Notes: Abstract. We study (inverse) photoemission from systems with strong coupling of doped carriers to phonons. Using an adiabatic approximation, we develop a method for calculating spectra. This method is particularly simple for systems where the electron-phonon coupling can be neglected in the initial state, e.g., the undoped t-J model. The theory then naturally explains why the electron-phonon coupling just leads to a broadening of spectra calculated without electron-phonon coupling, without changing the dispersion. This is in agreement with recent angle-resolved photoemission spectroscopy (ARPES) on undoped cuprates, and it supports the interpretation in terms of strong electron-phonon interaction. The theory also shows that for systems with strong electron-phonon coupling in the initial state, the result cannot in general be related to the spectrum obtained without electron-phonon coupling.
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    Melting and evaporation transitions in small Al clusters: canonical Monte-Carlo simulations (2005)
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    The European physical journal 43 (2005), S. 47-52 
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    Notes: Abstract. A dimer of bound atoms cannot melt, only dissociate. Bulk metals show a well defined first order transition between their solid and liquid phases. The appearance of the melting transition is explored for increasing clusters sizes via the signatures in the specific heat and the root mean square of the bond lengths δB (Berry parameter) by means of Monte-Carlo simulations of Al clusters modelled by Gupta potentials. Clear signatures of a melting transition appear for N∼6 atoms. Closed-shell effects are shown for clusters with up to 56 atoms. The melting transition is compared in detail with the dissociation transition, which induces a second and possibly much larger local maximum in the specific heat at higher temperatures. Larger clusters are shown to fragment into dimers and trimers, which in turn dissociate at higher temperatures.
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    Phase diagram in the quantum XY model with long-range interactions (2005)
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    The European physical journal 43 (2005), S. 93-96 
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    Notes: Abstract. We study the d-dimensional quantum XY model with ferromagnetic long-range interaction decaying as r-p in terms of boson operators, by employing the coherent state path integral approach. We have obtained a finite critical temperature as a function of the dimension (d) for d〈p〈2d. For p〉2d the system becomes disordered at all temperatures. For the particular values p=3/2 and d=1 our theoretical calculations are comparable to those from Monte Carlo simulations.
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    On the properties of cycles of simple Boolean networks (2005)
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    The European physical journal 43 (2005), S. 115-124 
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    Notes: Abstract. We study two types of simple Boolean networks, namely two loops with a cross-link and one loop with an additional internal link. Such networks occur as relevant components of critical K=2 Kauffman networks. We determine mostly analytically the numbers and lengths of cycles of these networks and find many of the features that have been observed in Kauffman networks. In particular, the mean number and length of cycles can diverge faster than any power law.
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    Diagram technique for finding of vertex functions in the Landau theory of heteropolymer liquids (2005)
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    The European physical journal 43 (2005), S. 251-269 
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    Notes: Abstract. The problem on finding the coefficients of the Landau free energy expansion into the power series of parameter of order has been considered for solutions and melts of linear heteropolymers whose molecules comprise several types monomeric units arranged stochastically. The presence of such a quenched structural disorder places this problem outside the framework of the traditional statistical physics inviting for its solution special approaches. One of them, based on the replica concept and actively engaged in theoretical physics of disordered systems, has been invoked in this paper to derive expressions for the vertex functions in the Landau theory of heteropolymer liquids. An algorithm has been formulated which permits one resorting to the simple diagram technique to write down expressions for these functions of any order in terms of the statistical characteristics of chemical quenched structure of polymer molecules. Explicit expressions for the contributions to the Landau free energy up to the fourth degree of order parameters for polymer systems with an arbitrary structural disorder have been presented to illustrate this general algorithm. Its potentialities have been also exemplified for the melt of random m-component copolymer where exact analytical formulas for these contributions up to n=6 at an arbitrary m have been derived for the first time.
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    Crossover component in non critical dissipative sandpile models (2005)
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    The European physical journal 43 (2005), S. 213-220 
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    Notes: Abstract. The effect of bulk dissipation on non critical sandpile models is studied using both multifractal and finite size scaling analyses. We show numerically that the local limited (LL) model exhibits a crossover from multifractal to self-similar behavior as the control parameters hext and epsilon turn towards their critical values, i.e. hext →0+ and epsilon→epsilonc. The critical exponents are not universal and exhibit a continuous variation with epsilon. On the other hand, the finite size effects for the local unlimited (LU), non local limited (NLL), and non local unlimited (NLU) models are well described by the multifractal analysis for all values of dissipation rate epsilon. The space-time avalanche structure is studied in order to give a deeper understanding of the finite size effects and the origin of the crossover behavior. This result is confirmed by the calculation of the susceptibility.
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    Magnetic AC susceptibility of stoichiometric and low zinc doped magnetite single crystals (2005)
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    The European physical journal 43 (2005), S. 201-212 
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    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. Systematic studies of AC susceptibility in a stoichiometric magnetite single crystal, in a series of low zinc doped magnetite (xZn 〈 0.04) and in nonstoichiometric magnetite samples (both single crystals and pellets) in the temperature range 4–300 K are presented. Measurements were performed in several AC fields ( $H_{AC}=0.2{-}20\ $ Oe) and at different frequencies (15–6000 Hz). It is suggested that the signal is primarily due to magnetic domain wall movement, strongly influenced by structural domains (twins). Two sets of anomalies were found: the first is associated with the Verwey transition and the second involves two different effects, one at 28 K, observed only in stoichiometric magnetite, and the other at 50 K. While the temperature position of the first anomaly (28 K) does not depend on frequency, the effect at 50 K is associated with an activation process, shifting to higher temperatures with increasing frequency. This last effect may be linked to the low temperature magnetoelectric effects terminating approximately at those temperatures. Qualitatively similar results have been observed by the Magnetic After Effect technique presented in the literature, that is associated with relaxation times that are 104 higher than those characteristic of our technique.
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    URL: http://dx.doi.org/10.1140/epjb/e2005-00043-5
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    Nonextensive thermostatistic properties of a q-generalized Fermi system (2005)
    Springer
    The European physical journal 43 (2005), S. 271-277 
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    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. Based on the generalized statistic distribution derived from the Tsallis’ entropy that has been successfully used in complex systems with long-range interactions and/or long-duration memory, the thermostatistic properties of a q-generalized Fermi system are studied. The total number of particles, internal energy, and heat capacity at constant volume are calculated for two different cases of q≤1 and q≥1, respectively, where q is an important parameter to evaluate the nonextensivity of the system. The thermostatistic characteristics of the system are discussed in detail. It is found from the results obtained here that the Fermi energy of such a system is independent of the parameter q and is equal to that of an original ideal Fermi system when q≤1, while other thermostatistic properties of the system depend closely on the parameter q. For example, when q〈1, the chemical potential of the system in certain region of temperature may be larger than the Fermi energy; when q〉1, some thermodynamic parameters of the system at low temperatures must be cut off.
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    URL: http://dx.doi.org/10.1140/epjb/e2005-00048-0
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    Fermion kinetics in the Falicov-Kimball limit of the three-band Emery model (2005)
    Springer
    The European physical journal 43 (2005), S. 319-331 
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    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. The three-band Emery model is reduced to a single-particle quantum model of Falicov-Kimball type, by allowing only up-spins to hop, and forbidding double occupation by projection. It is used to study the effects of geometric obstruction on mobile fermions in thermodynamic equilibrium. For low hopping overlap, there appears a plateau in the entropy, due to charge correlations, and related to real-space disorder. For large overlap, the equilibrium thermopower susceptibility remains anomalous, with a sign opposite to the one predicted from the single-particle density of states. The heat capacity and non-Fermi liquid response are discussed in the context of similar results in the literature. All results are obtained by evaluation of an effective single-particle free-energy operator in closed form. The method to obtain this operator is described in detail.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1140/epjb/e2005-00059-9
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    The investigation of the magnetodielectric effect in multiferroic ferroelectromagnets (2005)
    Springer
    The European physical journal 43 (2005), S. 333-338 
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    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. In multiferroic ferroelectromagnets, microscopic coupling interaction between the ferroelectric and magnetic order results in the macroscopic correlation between the dielectric and magnetic properties, which is defined as magnetodielectric effect. If we classify multiferroic ferroelectromagnets as two kinds: ferroelectric-ferromagnets and ferroelectric-antiferromagnets, we find the magnetodielectric behavior of these two kinds of ferroeletromagnets show obvious difference. We analyze the origin of the different magnetodielectric behavior and find that the fluctuation of the spin-pair correlation plays a critical role. Soft-mode theory based on DIFFOUR model and the mean-field theory are combined to deal with multiferroic ferroelectromagnetic system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1140/epjb/e2005-00060-4
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    Electrical and magnetic properties of Gd(Ba2-xLax)Cu3O7+δ (2005)
    Springer
    The European physical journal 43 (2005), S. 305-318 
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    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. We have studied the structural, electrical, and magnetic properties of the normal and superconducting states Gd(Ba2-xLax)Cu3O7+δ [Gd(BaLa)123] samples with 0.0 ≤x ≤0.8 prepared by the standard solid-state reaction. XRD characterization shows an orthorhombic-tetragonal structural transition at x=0.2. Iodometric titration analysis shows the oxygen content of the samples increase with the increase of La doping. The resistivity curves show that for x≤0.15, there is metallic behavior, and for x≥0.2, there is a gradual insulating transition behavior in the normal state. The metal-insulator and superconductor-insulator transitions occur between x=0.35 and x=0.4. The superconducting transition temperature decreases with the increase of La content as two-step curve. The normal-state resistivity is fitted for two and three dimensional variable range hopping (2D&3D-VRH) and Coulomb gap (CG) regimes, separately. The results show that the dominant mechanism is CG for x≤0.35, and VRH for x≥0.4. The pinning energy U, derived from the thermally activated flux creep (TAFC) model and Ambegaokar-Halperin (AH) theory, shows a power-law relation as U∼H -β. The critical current density decreases with the increase of La doping and magnetic field. The E-J curves show that the induced electric field increases with the increase of magnetic field and La concentration. The magnetization measurements indicate that the critical penetration fields and magnetic current density decrease with La doping.
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    URL: http://dx.doi.org/10.1140/epjb/e2005-00058-x
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    Polaron properties in ternary group-III nitride mixed crystals (2005)
    Springer
    The European physical journal 43 (2005), S. 339-345 
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    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. Polaron properties are studied in bulk wurtzite nitride ternary mixed crystals AxB1-xN (A, B = Al, Ga, In) with the use of a dielectric continuum Fröhlich-like electron-phonon interaction Hamiltonian. The polaronic self-trapping energy and effective mass are analytically derived by taking the mixing properties of the LO and TO polarizations due to the anisotropy effect into account in the mono-phonon approximation. The numerical computation has been performed for the wurtzite ternary mixed crystal materials InxGa1-xN, AlxGa1-xN, and AlxIn1-xN as functions of the composition x. The results show that the polaronic self-trapping energies in the wurtzite structures are bigger than that in zinc-blende structures for the materials calculated. It is also found that the structure anisotropy increases the electron-phonon interaction in wurtizte nitride semiconductors. The results indicate that the LO-like phonon influence on the polaronic self-trapping energy and effective mass is dominant, and the anisotropy effect is obvious.
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    URL: http://dx.doi.org/10.1140/epjb/e2005-00061-3
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    The H+ related defects involved in domain reversal for both near-stoichiometric and heavily Mg-doped lithium niobate crystals (2005)
    Springer
    The European physical journal 43 (2005), S. 347-353 
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    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. Domain reversal was performed on both near-stoichiometric and heavily Mg-doped lithium niobate crystals. H+ related defect structures in these two types of crystals were studied through the infrared absorption spectra. It is found that the intensity of some decomposed peaks of absorption band change apparently during domain reversal for near-stoichiometric lithium niobate crystals but not for heavily Mg-doped lithium niobate crystals. According to these experimental results, distinct models about H+ related defect structure in LiNbO3 lattice were supposed for them. Nb4+Li and Mg3-Nb were considered as the centers of H+ related defect complex for near-stoichiometric and heavily Mg-doped lithium niobate crystals respectively. Different behavior of them was used to explain the difference of infrared absorption spectra during domain reversal between two types of crystals.
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    URL: http://dx.doi.org/10.1140/epjb/e2005-00062-2
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    Dimer site-bond percolation on a square lattice (2005)
    Springer
    The European physical journal 43 (2005), S. 363-368 
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    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. A generalization of the pure site and pure bond percolation problems in which pairs of nearest neighbor sites (site dimers) and linear pairs of nearest neighbor bonds (bond dimers) are independently occupied at random on a square lattice is studied. We called this model as dimer site-bond percolation. Motivated by considerations of cluster connectivity, we have used two distinct schemes (denoted as $S\cap B$ and $S\cup B$ ) for dimer site-bond percolation. In $S \cap B$ ( $S \cup B$ ), two points are said to be connected if a sequence of occupied sites and (or) bonds joins them. By using finite-size scaling theory, data from $S \cap B$ and $S \cup B$ are analyzed in order to determine i) the phase boundary between the percolating and non-percolating regions and ii) the numerical values of the critical exponents of the phase transition occurring in the system. The results obtained are discussed in comparison with the corresponding ones for classical monomer site-bond percolation.
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    A molecular dynamics investigation of dynamical heterogeneity in supercooled water (2005)
    Springer
    The European physical journal 43 (2005), S. 355-362 
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    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. We investigate the presence of dynamical heterogeneity in supercooled water with molecular dynamics simulations using the new water model proposed by Mahoney and Jorgensen [M.W. Mahoney, W.L. Jorgensen J. Chem. Phys. 112, 8910 (2000)]. Prompted by recent theoretical results [J.P. Garrahan, D. Chandler, Phys. Rev. Lett. 89, 35704 (2002)] we study the dynamical aggregation of the least and the most mobile molecules. We find dynamical heterogeneity in supercooled water and string-like dynamics for the most mobile molecules. We also find the dynamical aggregation of the least mobile molecules. The two kinds of dynamical aggregation appear however to be very different. Characteristic times are different and evolve differently. String-like motions appear only for the most mobile molecules, a result predicted by the facilitation theory. The aggregation of the least mobile molecules is more organized than the bulk while the opposite is observed for the most mobile molecules.
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    URL: http://dx.doi.org/10.1140/epjb/e2005-00063-1
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    Self organized scale-free networks from merging and regeneration (2005)
    Springer
    The European physical journal 43 (2005), S. 369-372 
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    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. We propose that the ubiquitous scale free nature of many real world networks may emerge from a steady state process where nodes are created and merged randomly. The merging may be viewed as an optimization of efficiency by minimizing redundancy.
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    URL: http://dx.doi.org/10.1140/epjb/e2005-00065-y
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    Ground-state correlations and finite temperature properties of the transverse Ising model (2005)
    Springer
    The European physical journal 43 (2005), S. 373-378 
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    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. We present a semi-analytic study of Ising spins on a simple square or cubic lattice coupled to a transverse magnetic field of variable strength. The formal analysis employs correlated basis functions (CBF) theory to investigate the properties of the corresponding N-body ground and excited states. For these states we discuss two different ansaetze of correlated trial wave functions and associated longitudinal and transverse excitation modes. The formalism is then generalized to describe the spin system at nonzero temperatures with the help of a suitable functional approximating the Helmholtz free energy. To test the quality of the functional in a first step we perform numerical calculations within the extended formalism but ignore spatial correlations. Numerical results are reported on the energies of the longitudinal and the transverse excitation modes at zero temperature, on critical data at finite temperatures, and on the optimized spontaneous magnetization as a function of temperature and external field strength.
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    URL: http://dx.doi.org/10.1140/epjb/e2005-00066-x
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    Integrable spin-boson interaction in the Tavis-Cummings model from a generic boundary twist (2005)
    Springer
    The European physical journal 43 (2005), S. 387-391 
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    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. We construct models describing interaction between a spin s and a single bosonic mode using a quantum inverse scattering procedure. The boundary conditions are generically twisted by generic matrices with both diagonal and off-diagonal entries. The exact solution is obtained by mapping the transfer matrix of the spin-boson system to an auxiliary problem of a spin-j coupled to the spin-s with general twist of the boundary condition. The corresponding auxiliary transfer matrix is diagonalized by a variation of the method of Q-matrices of Baxter. The exact solution of our problem is obtained applying certain large-j limit to su(2)j, transforming it into the bosonic algebra.
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    URL: http://dx.doi.org/10.1140/epjb/e2005-00068-8
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    Acoustic radiation force due to incident plane-progressive waves on coated spheres immersed in ideal fluids (2005)
    Springer
    The European physical journal 43 (2005), S. 379-386 
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    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. In this study, the acoustic radiation force resulting from the interaction of a plane progressive wave with a coated sphere was examined. The linear acoustic scattering problem was obtained first by solving the classical boundary conditions to obtain the required coefficients. The radiation force was then determined by averaging the momentum flux tensor expressed in terms of the total scattering pressure or velocity potential in an ideal fluid. Numerical calculations of the radiation force function Yp , which is the radiation force per unit energy density and unit cross-section, were displayed versus the dimensionless size parameter x=k1 b (k1 is the wave number in the exterior fluid and b the radius of the uncoated sphere) over a large range of frequencies. Particular emphasis has been focused on the coating thickness and the absorption of sound inside the outer covering layer. The fluid-loading effect on the radiation force function curves was also analysed.
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    URL: http://dx.doi.org/10.1140/epjb/e2005-00067-9
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    Rayleigh-Schrödinger-Goldstone variational perturbation theory for many Fermion systems (2005)
    Springer
    The European physical journal 43 (2005), S. 393-398 
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    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. We present a Rayleigh-Schrödinger-Goldstone perturbation formalism for many Fermion systems. Based on this formalism, variational perturbation scheme which goes beyond the Gaussian approximation is developed. In order to go beyond the Gaussian approximation, we identify a parent Hamiltonian which has an effective Gaussian vacuum as a variational solution and carry out further perturbation with respect to the renormalized interaction using Goldstone’s expansion. Perturbation rules for the ground state wavefunctional and energy are found, thus, opening a way for general use of the Schrödinger picture method for many Fermion systems. Useful commuting relations between operators and the Gaussian wavefunctional are also found, which could reduce the calculational efforts substantially. As examples, we calculate the first order correction to the Gaussian wavefunctional and the second order correction to the ground state of an electron gas system with the Yukawa-type interaction.
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    URL: http://dx.doi.org/10.1140/epjb/e2005-00069-7
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    Spin-polarized transport through a coupled double-dot (2005)
    Springer
    The European physical journal 43 (2005), S. 421-427 
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    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. We investigate the quantum transport through a mesoscopic device consisting of an open, lateral double-quantum-dot coupled by time oscillating and spin-polarization dependent tunneling which results from a static magnetic field applied in the tunneling junction. In the presence of a non-vanishing bias voltage applied to two attached macroscopic leads both spin and charge currents are driven through the device. We demonstrate that the spin and charge currents are controllable by adjusting the gate voltage, the frequency of driving field and the magnitude of the magnetic field as well. An interesting resonance phenomenon is observed.
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    URL: http://dx.doi.org/10.1140/epjb/e2005-00072-0
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    Dimensional reduction of the Abelian Higgs Carroll-Field-Jackiw model (2005)
    Springer
    The European physical journal 38 (2005), S. 511-519 
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    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. Taking as a starting point a Lorentz non-invariant abelian Higgs model defined in 1 + 3 dimensions, we carry out its dimensional reduction to D = 1 + 2, obtaining a new planar model composed by a Maxwell-Chern-Simons-Proca gauge sector, a massive scalar sector, and a mixing term (involving the fixed background $v^{\mu}$ ) that imposes the Lorentz violation to the reduced model. The propagators of the scalar and massive gauge field are evaluated and the corresponding dispersion relations determined. Based on the poles of the propagators, a causality and unitarity analysis is carried out at tree level. We then show that the model is totally causal, stable and unitary.
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    URL: http://dx.doi.org/10.1140/epjc/s2004-02033-x
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