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  • Springer  (173,866)
  • American Institute of Physics (AIP)  (26,481)
  • 2000-2004  (200,347)
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  • 1
    Unknown
    London ; New York : Springer
    Decision engineering  
    Keywords: Decision making, Mathematical models. ; Decision making, Methodology.
    Pages: ix, 172 p.
    ISBN: 1-85233-864-4
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  • 2
    Keywords: Semantic Web, Congresses.
    Pages: x, 145 p.
    ISBN: 3-540-25982-1
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  • 3
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    The European physical journal 21 (2004), S. 161-167 
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. Virtual radiative corrections due to the long-range Coulomb forces of heavy nuclei with charge Z may lead to sizeable corrections to the Born cross-section usually used for lepton-nucleus scattering processes. An introduction and presentation of the most important issues of the eikonal approximation is given. We present calculations for forward electroproduction of rho-mesons in a framework suggested by the VDM (vector dominance model), using the eikonal approximation. It turns out that Coulomb corrections may become relatively large. Some minor errors in the literature are corrected.
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  • 4
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    The European physical journal 21 (2004), S. 29-36 
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. Positive pion electroproduction from the deuteron near threshold has been considered within an approach based on the unitary transformation method. The gauge independence of the treatment is provided by using an explicitly gauge-independent expression for the reaction amplitude. The results of calculations for the kinematics of the experiments on forward-angle $\pi^ + $ meson electroproduction accomplished at Saclay and Jefferson Laboratory are discussed and compared with those given by the impulse approximation. It is shown that the observed behaviour of the cross-sections is in accordance with the calculations based on the pion-nucleon dynamics. In particular, the pion production rate suppression in the $^2{\rm H}({\rm e,e}'\pi^ + $ )nn reaction compared to that for the $^1{\rm H}({\rm e,e}'\pi^ + $ )n one can be due to such “nuclear medium” effects as nucleon motion and binding along with Pauli blocking in the final nn state.
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  • 5
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    The European physical journal 21 (2004), S. 57-60 
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. We calculate, for the first time, the state-dependent pairing gap of a finite nucleus (120Sn) diagonalizing the bare nucleon-nucleon potential (Argonne v 14) in a Hartree-Fock basis (with effective k-mass $m_k \approx 0.7 m$ ), within the framework of the generalized Bogoliubov-Valatin approximation including scattering states up to 800 MeV above the Fermi energy to achieve convergence. The resulting gap accounts for about half of the experimental gap. The combined effect of the bare nucleon-nucleon potential and of the induced pairing interaction arising from the exchange of low-lying surface vibrations between nucleons moving in time-reversal states close to the Fermi energy accounts for the experimental gap.
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  • 6
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    The European physical journal 21 (2004), S. 79-85 
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. In many applications of the intranuclear-cascade (INC) model to spallation reactions, all nucleons in the target are assumed to move in a common potential well. However, the potential depth should depend upon nucleon isospin and energy. The present paper describes the first results obtained after the introduction of these features in the Liége INCL3 model. It is shown that such modifications change cascade particle multiplicities significantly but total particle multiplicities are only slightly altered. Nucleon inclusive cross-sections are not modified significantly, except in the region of the quasi-elastic peaks. In particular, the centroid of the peak in neutron double differential cross-sections relative to proton-induced reactions can be sizeably shifted toward larger energy losses, as is observed experimentally. Implications of these results are discussed.
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  • 7
    ISSN: 1434-601X
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    Topics: Physics
    Notes: Abstract. Multi-nucleon transfer reactions in 40Ca + 208Pb have been studied at several bombarding energies close to the Coulomb barrier. Light reaction products have been identified in mass and charge with a time-of-flight spectrometer. The energy spectra of the inclusive two-neutron pick-up channel show a population in a narrow region of excitation energies which corresponds to the predicted energy of pairing-vibration states in 42Ca.
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  • 8
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    The European physical journal 21 (2004), S. 75-77 
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. The very neutron-deficient nuclide 129Pm was produced via the 92Mo(40Ca, p2n) reaction and identified for the first time by using the X- $\gamma $ coincidence in combination with a He jet tape transport system. According to the decay curve of a 99 keV $\gamma $ -ray which corresponds to the known $5/2^{-} \rightarrow 1/2^{-}$ transition in the daughter nucleus 129Nd of the 129Pm decay, the half-life of 129Pm was determined to be 2.4(9) s. Based on the nuclear potential energy surface (PES) calculations, the ground-state spin-parity of 129Pm was predicted as 5/2- which is favorable to feed a 5/2- low-lying state in the daughter nucleus 129Nd via the (EC $ + \beta^{ + }$ ) decay.
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  • 9
    ISSN: 1434-601X
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    Topics: Physics
    Notes: Abstract. Doubly differential electron velocity spectra induced by 36Ar18 + (95 MeV/u) from thin target foils (C, Ni, Ag, Au) were measured at GANIL (Caen, France) by means of the ARGOS multidetector and the time-of-flight technique. The main features observed in the forward spectra are convoy electrons, binary-encounter electrons, and (for the Au target only) a high-velocity tail which we attribute to a “Fermi shuttle” acceleration mechanism. Backward spectra do not show distinct structures. The spectra allow us to determine absolute singly differential cross-sections as a function of the target material and the emission angle. The convoy electron yield increases with the target atomic number, but for C their yield is so small that our experiment is not able to detect them. Absolute doubly differential cross-sections for binary-encounter electron ejection from C targets are well described by a transport theory which is based on the relativistic electron impact approximation (EIA) for electron production and which accounts for angular deflection, energy loss and energy straggling of the transmitted electrons.
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  • 10
    ISSN: 1434-601X
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    Topics: Physics
    Notes: Abstract. Lifetimes have been measured for dipole bands in 141Eu using DSAM. The deduced B(M1) and B(E2) values as well as B(M1)/B(E2) ratios are compared with calculations in the framework of the TAC (Tilted Axis Cranking) and SPAC (Shears mechanism with Principal Axis Cranking) models. The dipole bands can be interpreted as magnetic rotational bands.
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  • 11
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    The European physical journal 21 (2004), S. 93-116 
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. Electromagnetic and Lorentz-scalar form factors are calculated for a bound system of two spin-less particles exchanging a zero-mass scalar particle. Different approaches are considered including solutions of a Bethe-Salpeter equation, a “point form” approach to relativistic quantum mechanics and a non-relativistic one. The comparison of the Bethe-Salpeter results, which play the role of an “experiment” here, with the ones obtained in “point form” in single-particle approximation, evidences sizable discrepancies, pointing to large contributions from two-body currents in the latter approach. These ones are constructed using two constraints: ensuring current conservation and reproducing the Born amplitude. The two-body currents so obtained are qualitatively very different from standard ones. Quantitatively, they turn out not to be sufficient to remedy all the shortcomings of the “point form” form factors evidenced in impulse approximation.
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  • 12
    ISSN: 1434-601X
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    Topics: Physics
    Notes: Abstract. High-spin states in 160,161,162Ho have been populated in the reactions 158,160Gd(7Li, xn) at 56 MeV. In all three isotopes the known rotational bands have been extended to significantly higher spin. In 160 Ho, the band crossing in the $\pi$ 7/2-[523] $\otimes$ $\nu$ 11/2-[505] band has been observed for the first time. The sequences built on the proton 7/2-[523], 7/2 + [404], 1/2 + [411] and 1/2-[541] states in 161Ho have been extended up to spin 51/2-, 35/2 + , 51/2 + and 41/2-, respectively, leading to the first observation of upbends in all four cases. In addition, a new band most probably belonging to this nucleus has been identified. In the most neutron-rich isotope 162Ho, the only known rotational band, which is built on the $\pi$ 7/2-[523] $\otimes$ $\nu$ 5/2 + [642] configuration, has been extended up to the 28- state. The properties of all observed bands are discussed and compared to the neighbouring isotopes.
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  • 13
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    The European physical journal 21 (2004), S. 133-143 
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. We compute the spectra of exotic pentaquarks and monopole excitations of thelow-lying $\frac{1}{2}^ + $ and $\frac{3}{2}^ + $ baryons in a chiral soliton model. Once the low-lying baryon properties are fit, the other states are predicted without any more adjustable parameters. This approach naturally leads to a scenario in which the mass spectrum of the next to lowest-lying $J^\pi = \frac{1}{2}^ + $ states is fairly well approximatedby the ideal mixing pattern of the $\mathbf{8}\oplus\overline{\mathbf{10}}$ representation of flavor SU(3). We compare our results to predictions obtained in other pictures for pentaquarks and speculate about the spin-parity assignment for $\Xi(1690)$ and $\Xi(1950)$ .
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  • 14
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    The European physical journal 21 (2004), S. 61-66 
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. Using recent experimental information for the 132Sn region, an empirical Hamiltonian is obtained by some modifications of a Hamiltonian (CW5082) originally derived from the 208Pb region. Shell model calculations with the new Hamiltonian show a remarkable improvement in the predictive power when compared with the available experimental results. It overcomes many limitations of the CW5082 Hamiltonian in this region, specially for $N\geq 84$ isotones. The calculated level spectra and B(E2) values with the new Hamiltonian, also compare well with the available results calculated with the CD-Bonn and SKX Hamiltonians, reflecting consistency in the wave function structure at least in the low-lying regions. An interesting behaviour of effective charges is revealed in this region. It is shown that a drastic reduction of proton effective charge is necessary for obtaining B(E2) values for the N = 84 isotones. Neutron effective charge is found to be in the range (0.62-0.72)e. We predict the spectroscopic properties of 135,136Sn not yet known experimentally. Further improvement of the modified Hamiltonian is also initiated.
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  • 15
    ISSN: 1434-601X
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    Topics: Physics
    Notes: Abstract. The beta-decay of 232Fr to excited states in 232Ra has been studied using gamma-gamma coincidence detection combined with the isotope separator on-line technique at the ISOLDE PSB facility at CERN. Earlier findings are confirmed and three new gamma lines are reported. In addition to the beta-decay characteristics of 232Fr, the K = 0 ground-state band in 232Ra is identified. A yield survey of neutron-rich Fr isotopes, important also for the EURISOL project, is incorporated.
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  • 16
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    The European physical journal 21 (2004), S. 145-153 
    ISSN: 1434-601X
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    Topics: Physics
    Notes: Abstract. We perform an adjustment to the most recent structure function data, considering the QCD dipole picture applied to the ep scattering. The structure function F 2 at small x and intermediate Q 2 can be described by the model containing an economical number of free parameters, which encodes the hard-pomeron physics. The structure function F L and the gluon distribution are predicted without further adjustments. The data description is remarkably good, however giving a rather low value for the fixed strong-coupling constant. This indicates that a resummed next-to-leading-level analysis should be done, which would bring it to suitable values.
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  • 17
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    The European physical journal 21 (2004), S. 155-159 
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. The electromagnetic radius of a charged pion and the transition radius of a neutral pion are calculated in the framework of the nonlocal chiral quark model. It is shown in this model that the vector meson contributions to the pion radii are noticeably suppressed in comparison with a similar contribution in the local Nambu-Jona-Lasinio model. The form factor for the process $\gamma^*\pi^ + \pi^-$ is calculated for -1 GeV2〈 q 2 〈 1.6 GeV2. Our results are in satisfactory agreement with experimental data.
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  • 18
    ISSN: 1434-601X
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    Topics: Physics
    Notes: Abstract. We study kaonic hydrogen, the bound K - p state A K p . Within a quantum field theoretic and relativistic covariant approach we derive the energy level displacement of the ground state of kaonic hydrogen in terms of the amplitude of K - p scattering for arbitrary relative momenta. The amplitude of low-energy K - p scattering near threshold is defined by the contributions of three resonances $\Lambda(1405)$ , $\Lambda(1800)$ and $\Sigma^0(1750)$ and a smooth elastic background. The amplitudes of inelastic channels of low-energy K - p scattering fit experimental data on the near-threshold behaviour of the cross-sections and the experimental data by the DEAR Collaboration. We use the soft-pion technique (leading order in Chiral Perturbation Theory) for the calculation of the partial width of the radiative decay of pionic hydrogen $A_{\pi p} \to n + \gamma$ and the Panofsky ratio. The theoretical prediction for the Panofsky ratio agrees well with experimental data. We apply the soft-kaon technique (leading order in Chiral Perturbation Theory) to the calculation of the partial widths of radiative decays of kaonic hydrogen $A_{Kp} \to \Lambda^0 + \gamma$ and $A_{K p} \to \Sigma^0 + \gamma$ . We show that the contribution of these decays to the width of the energy level of the ground state of kaonic hydrogen is less than 1 $\%$ .
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  • 19
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    The European physical journal 21 (2004), S. 117-131 
    ISSN: 1434-601X
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    Topics: Physics
    Notes: Abstract. We extend a recent chiral approach to nuclear matter by including the most general (momentum-independent) NN-contact interaction. Iterating this two-parameter contact vertex with itself and with one-pion exchange the emerging energy per particle exhausts all terms possible up to and including fourth order in the small momentum expansion. Two (isospin-dependent) cut-offs $\Lambda_{0,1}$ are introduced to regularize the (linear) divergences of some three-loop in-medium diagrams. The equation of state of pure neutron matter, $\bar E_n(k_n)$ , can be reproduced very well up to quite high neutron densities of $\rho_n = 0.5 \mathrm{fm}^{-3}$ by adjusting the strength of a repulsive nn-contact interaction. Binding and saturation of isospin-symmetric nuclear matter is a generic feature of our perturbative calculation. Fixing the maximum binding energy per particle to $-\bar E(k_{f0}) = 15.3 $ MeV we find that any possible equilibrium density $\rho_0$ lies below $\rho_0^{\rm max} = 0.191 \mathrm{fm}^{-3}$ . The additional constraint from the neutron matter equation of state leads however to a somewhat too low saturation density of $\rho_0 = 0.134 \mathrm{fm}^{-3}$ . We also investigate the effects of the NN-contact interaction on the complex single-particle potential U(p,k f ) + i W(p,k f ). We find that the effective nucleon mass at the Fermi surface is bounded from below by $M^*(k_{f0}) \geq 1.4 M$ . This property keeps the critical temperature of the liquid-gas phase transition at somewhat too high values $T_{\rm c} \geq 21 $ MeV. The downward bending of the asymmetry energy A(k f ) above nuclear-matter saturation density is a generic feature of theapproximation to fourth order. We furthermore investigate the effects of the NN-contact interaction on the $(\mathop{\nabla}\limits^{\to} \rho)^2$ -term in the nuclear energy density functional ${\cal E}[\rho,\tau]$ . Altogether, there is within this complete fourth-order calculation no “magic” set of adjustable short-range parameters with which one could reproduce simultaneously and accurately all semi-empirical properties of nuclear matter. In particular, the conditions for a good neutron matter equation of state and for good single-particle properties are mutually exclusive.
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  • 20
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    The European physical journal 20 (2004), S. A13 
    ISSN: 1434-601X
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  • 21
    ISSN: 1434-601X
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    Topics: Physics
    Notes: Abstract. For a level scheme investigation of 144Gd an experiment with the $\gamma$ -spectrometer EUROBALL III has been carried out and lifetimes have been measured with the $\gamma$ -spectrometer GASP using the Doppler-shift attenuation method. The high-spin states have been populated in these experiments by means of the 100Mo(48Ti,4n) reaction at 215 MeV and the 114Cd(36S,6n) reaction at E = 182 MeV, respectively. The known quadrupole band has been modified and a new one has been established. Reduced E2 transition probabilities B(E2) were determined for seven members of these quadrupole bands. They show values between $\approx 60$ and 130 W.u. and this considerable enhancement gives evidence for a significant nuclear deformation. A $(\pi h_{11/2})^2 \otimes (\nu h_{11/2})^{-2}$ configuration may be assigned to one of the quadrupole bands according to total Routhian surface calculations. The spin dependence of the B(E2) values has been explained by IBM calculations involving high-spin quasiparticle excitations.
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  • 22
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    Experiments in fluids 6 (2004), S. 119-128 
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract An automated particle image velocimeter has been constructed to determine fluid velocity fields by directly measuring particle image separations. A new image shifting technique eliminates directional ambiguity from velocity measurements. Theoretical and practical considerations in implementing the PIV system are presented. Using a simple, known flow field to investigate system performance, RMS errors of less than 0.7% of full scale are achieved, and at low seeding density fewer than 10% of velocity measurements produce bad data. Applications of system measurements to the instantaneous velocity field of an axisymmetric jet are presented.
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  • 23
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    Experiments in fluids 6 (2004), S. 129-135 
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The triangular jet was investigated for use as a passive device to enhance fine-scale mixing and to reduce the coherence of large-scale structures in the flow. The suppression of the structures is vital to the enhancement of molecular mixing, which is important for efficient chemical reactions including combustion. The sharp corners in the jet injector introduced high instability modes into the flow via the non-symmetric mean velocity and pressure distribution around the nozzle. Both aerodynamic and hydrodynamic flows showed the difference between the flow at the corner (vertex) and at the flat side. While highly coherent structures could be generated at the flat side, the corner flow was dominated by highly turbulent small-scale eddies. The flow characteristics were tested using hotwire anemometry for mean flow and turbulence analysis, and flow visualization in air and water.
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  • 24
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    Experiments in fluids 6 (2004), S. 144-144 
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 25
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    Experiments in fluids 6 (2004), S. 73-79 
    ISSN: 1432-1114
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract This paper describes a piece of equipment which has been specially designed to permit the study of the evaporation of single liquid drops in an immiscible liquid at elevated pressures up to the order of 1 MPa. It is equipped with a piezoelectric discharger for yielding nucleation in each drop and with a dilatometer for detecting the change in volume of the drop in the course of evaporation succeeding the nucleation. Some preliminary results, obtained with the equipment, for n-pentane drops evaporating in a water medium at pressures up to 0.5 MPa (5 atm) are also presented.
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  • 26
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    Experiments in fluids 6 (2004), S. 80-88 
    ISSN: 1432-1114
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    Notes: Abstract Velocity bias effects on data obtained with a coincident two channel laser Doppler velocimeter in a highly turbulent separated supersonic flow are presented. Probability distributions of the fluctuating velocities were distorted by velocity bias in a manner consistent with theory and a two-dimensional velocity inverse weighting function bias correction produced reasonable appearing velocity probability distributions. The addition of an approximate correction term to account for the effects of the unmeasured third velocity component improved these results but had little effect on the velocity statistics. Experimental factors that could partially compensate or falsely add to the velocity bias, conditions for the bias to occur, and conditions for which the bias may also be observed and corrected for are discussed.
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  • 27
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    Experiments in fluids 6 (2004), S. 111-114 
    ISSN: 1432-1114
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    Notes: Abstract Two-dimensional flow fields and temperature boundary layer profiles around a heated and rotating circular cylinder in crossflow were experimentally investigated for a subcritical freestream-Reynolds-number 5.6 · 104 corresponding to a flow velocity of 7 m/s. Test parameter was the ratio of free stream velocity to peripheral speed, which encompasses the range between zero and 2.5. An electronically-controlled hot wire measurement technique, practicable for the requirements of 1–2 mm boundary layer thickness, was used. The numerous reliable test results confirm previous reported experiments. Characteristic features in heat transfer are discussed.
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    Experiments in fluids 6 (2004), S. 105-110 
    ISSN: 1432-1114
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    Notes: Abstract The present paper is concerned with the determination of the measuring position of a laser-Doppler anemometer (LDA) relative to a wall. The proposed method is based on the finding that the output of a hot-wire anemometer increases when the wire, which is mounted in quiescent air parallel to the wall, is brought closer than 800 μm to the wall. For given hot-wire anemometer parameters, the hot-wire anemometer output voltage depends on the wall material and the wire distance from the wall. After suitable calibration for the wall material of the test section, the anemometer reading in a test rig can be used to find the wire position. Moving the measuring volume of a LDA-system across the wire yields an output voltage variation of the LDA-photomultiplier showing a Gaussian shape. When the maximum output voltage is reached, the centre of the measuring control volume is located at the centre of the wire and, hence, the location of the LDA-measuring position is known. All position measurements for the LDA-system are then taken relative to this point using the scale of the LDA-traversing system. If optical effects of transparent test section walls are eliminated by employing refractive index matched liquids, there are other ways to find the measuring position of a laser-Doppler anemometer relative to a wall. One such method and its application to the study of the turbulent near wall flow in a pipe is described in this paper.
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  • 29
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    Experiments in fluids 6 (2004), S. 137-140 
    ISSN: 1432-1114
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  • 30
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    Experiments in fluids 6 (2004), S. 135-137 
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  • 31
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    Experiments in fluids 6 (2004), S. 140-143 
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  • 32
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    Experiments in fluids 6 (2004), S. 89-93 
    ISSN: 1432-1114
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    Notes: Abstract The deflection of laser light passing through the mildy heated, turbulent air stream in a lowspeed wind tunnel is measured by means of speckle photography. This optical wholefield method provides a dense distribution of data values of the deflection angle in the field of view. When isotropic turbulence is assumed, it becomes possible to calculate the correlation function of the three-dimensional, turbulent temperature (or density) field from the correlation function of the plane distribution of measured deflection angles. Spectra and characteristic length scales are determined and compared with cold-wire data reported in the literature.
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  • 33
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    Experiments in fluids 6 (2004), S. 94-104 
    ISSN: 1432-1114
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    Notes: Abstract An optical technique was used to study the dispersion of 50 μm, 90 μm and 150 μm droplets downstream of a source located in the center of a vertical pipe through which turbulent air is flowing. A turbulent dispersion coefficient, ɛ P, and a mean-square of the fluctuations in the turbulent velocity, v p 2 , are determined from the change of the measured mean-square displacement of the droplets over the pipe cross section with time. The interesting aspect of the experiments is that they explored conditions where the inertia of the particles is believed to be a much more important effect than that of the “crossing of trajectories” associated with the inequality of the average velocities of the particles and the fluid.
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  • 34
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    Experiments in fluids 6 (2004), S. 115-118 
    ISSN: 1432-1114
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    Notes: Abstract A simple method for the computer-aided calibration of an X-probe is described. This method requires the X-probe to be pitched in the free-stream at several velocities. From the corresponding output voltages, a calibration look-up table can be generated. The technique requires fewer assumptions than traditional methods based on King's law.
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    The European physical journal 32 (2004), S. 253-260 
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    Notes: Abstract. We review CP-violating effects in $Z \rightarrow 3$ jet and $Z \rightarrow$ 4 jet decays, assuming the presence of CP-violating effective $Z b \bar{b} G$ and $Z b \bar{b} G G$ couplings. Longitudinal beam polarization is included in the studies. We propose a direct search for such CP-violating couplings by using various CP-odd observables. The data of a future linear collider running at the Z-resonance in the so-called GigaZ option should give significant information on the couplings. Finally we show that stringent bounds on the mass of excited b quarks can be derived if appropriate couplings are of a size characteristic of a strong interaction.
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    The European physical journal 32 (2004), S. 269-280 
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    Notes: Abstract. In this article we calculate several divergent amplitudes in $\phi^4$ -theory on non-commutative space-time ( $\Theta_{0i} \neq 0$ ) in the framework of interaction-point time-ordered perturbation theory (IPTOPT), continuing work done in hep-th/0209253. On the ground of these results we find corresponding Feynman rules that allow for a much easier diagrammatic calculation of amplitudes. The most important feature of the present theory is the absence of the UV/IR mixing problem in all amplitudes calculated so far. Although we are not yet able to give a rigorous proof, we provide a strong argument for this result to hold in general. Together with the Feynman rules we found, this opens promising vistas onto the systematic renormalization of non-commutative field theories.
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    The European physical journal 32 (2004), S. 229-233 
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    Notes: Abstract. Entangled two-quantum states may be a sensitive probe for a loss of quantum coherence due to apparent violations of quantum mechanics, e.g. as caused by gravitation. We show that there exists a modest experiment sensitive to any one of the nine phenomenological parameters which describe decoherence in the neutral kaon system.
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    The European physical journal 32 (2004), S. 281-297 
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    Notes: Abstract. In this article we present explicit formulae for q-integration on quantum spaces which could be of particular importance in physics, i.e., q-deformed Minkowski space and q-deformed Euclidean space in three or four dimensions. Furthermore, our formulae can be regarded as a generalization of Jackson’s q-integral to three or four dimensions and provide a new possibility for an integration over the whole space being invariant under translations and rotations.
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    The European physical journal 32 (2004), S. 299-301 
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    The European physical journal 32 (2004), S. 575-582 
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    Notes: Abstract. We study ${\cal N} = 1$ supersymmetric U(N) gauge theory coupled to an adjoint scalar superfield with a cubic superpotential containing a multi trace term. We show that the field theory results can be reproduced from a matrix model whose potential is given in terms of a linearized potential obtained from the gauge theory superpotential by adding some auxiliary non-dynamical field. Once we get the effective action from this matrix model we could integrate out the auxiliary field getting the correct field theory results.
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    The European physical journal 32 (2004), S. 475-492 
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    Notes: Abstract. Searches for H Z production with the Higgs boson decaying into an invisible final state were performed using the data collected by the DELPHI experiment at centre-of-mass energies between 188 GeV and 209 GeV. Both hadronic and leptonic final states of the Z boson were analysed. In addition to the search for a heavy Higgs boson, a dedicated search for a light Higgs boson down to 40 GeV/c 2 was performed. No signal was found. Assuming the Standard Model HZ production cross-section, the mass limit for invisibly decaying Higgs bosons is 112.1 GeV/c 2 at 95% confidence level. An interpretation in the Minimal Supersymmetric extension of the Standard Model (MSSM) and in a Majoron model is also given.
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    The European physical journal 33 (2004), S. 53-61 
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    Notes: Abstract. In this paper, we discuss the feasibility of measuring deeply virtual Compton scattering (DVCS) on nuclei in a collider setting, as for example, the planned high-luminosity Electron-Ion Collider (EIC). We demonstrate that employing our recent model for nuclear generalized parton distributions (nGPDs), the one-photon unpolarized DVCS cross section as well as the azimuthal and spin asymmetry are of the same size as in the proton case. This will allow for an experimental extraction of nuclear GPDs with high precision, shedding new light not only on nuclear shadowing at small x Bj but also on the interplay of shadowing and nuclear enhancement at $x_{\mathrm{Bj}} \sim0.1$ .
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    The European physical journal 33 (2004), S. 123-136 
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    Notes: Abstract. We investigate the potential effects of the scalar flavor changing neutral currents that are generated e.g. in supersymmetry with $\tan\beta\gg1$ in the $b\rightarrow sl^ + l^-$ transitions. Using the experimental upper limit on ${\mathrm {BR}}(B^0_s\rightarrow\mu^ + \mu^-)$ we place stringent model independent constraints on the impact these currents may have on the rates ${\mathrm {BR}}(B\rightarrow X_s\mu^ + \mu^-)$ and ${\mathrm {BR}}(B\rightarrow K\mu^ + \mu^-)$ . We find that in the first case, contrary to the claim made recently in the literature, the maximal potential effects are always smaller than the uncertainty of the standard model NNLO prediction, that is of order 5-15%. In the second case, the effects can be large, but the experimental errors combined with the unsettled problems associated with the relevant form factors do not allow for any firm conclusion about the detectability of a new physics signal in this process. In supersymmetry the effects of the scalar flavor changing neutral currents are further constrained by the experimental lower limit on the B 0 s - $\bar B^0_s$ mass difference, so that most likely no detectable signal of the supersymmetry generated scalar flavor changing neutral currents in the processes $B\rightarrow X_s\mu^ + \mu^-$ and $B\rightarrow K\mu^ + \mu^-$ is possible.
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    The European physical journal 33 (2004), S. 41-52 
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    Notes: Abstract. We study the process $gg\to b\bar b H^ + H^-$ at large $\tan\beta$ , where it represents the dominant production mode of charged Higgs boson pairs in a Type II 2-Higgs doublet model, including the minimal supersymmetric standard model. The ability to select this signal would in principle enable the measurements of some triple-Higgs couplings, which in turn would help understanding the structure of the extended Higgs sector. We outline a selection procedure that should aid in disentangling the Higgs signal from the main irreducible background. This exploits a signature made up by “four b-quark jets, two light-quark jets, a $\tau$ -lepton and missing energy”. While, for $\tan\beta\gtrsim30$ and over a significant $M_{H^\pm}$ range above the top mass, a small signal emerges already at the Large Hadron Collider after 100 fb-1, ten times as much luminosity would be needed to perform accurate measurements of Higgs parameters in the above final state, rendering this channel a primary candidate to benefit from the so-called “Super” Large Hadron Collider option, for which a tenfold increase in instantaneous luminosity is currently being considered.
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    The European physical journal 33 (2004), S. 113-122 
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    Notes: Abstract. The nucleus-nucleus interaction is studied in the framework of the perturbative QCD with $N_c\to\infty$ and a fixed coupling constant. The pomeron tree diagrams are summed by an effective field theory. The classical field equations are solved by an iteration procedure, which is found to be convergent in a restricted domain of not too high energies and atomic numbers. The found gluon distributions do not scale, have their maxima close to 2 GeV $\!/c$ independent of rapidity and fall towards the central rapidity region. The cross-sections slowly grow with energy due to the contribution from peripheral collisions, where evolution remains linear. Simple variational estimates at higher rapidities confirm this tendency.
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    The European physical journal 33 (2004), S. 409-432 
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    Notes: Abstract. With the aim of generating new constraints on the OZI suppressed couplings of chiral perturbation theory a set of six equations of the Roy and Steiner type for the S- and P-waves of the $\pi K$ scattering amplitudes is derived. The range of validity and the multiplicity of the solutions are discussed. Precise numerical solutions are obtained in the range $E\lesssim 1$ GeV which make use as input, for the first time, of the most accurate experimental data available at $E\gtrsim 1$ GeV for both $\pi K\to\pi K$ and $\pi\pi\to K\overline{K}$ amplitudes. Our main result is the determination of a narrow allowed region for the two S-wave scattering lengths. Present experimental data below 1 GeV are found to be in generally poor agreement with our results. A set of threshold expansion parameters, as well as sub-threshold parameters are computed. For the latter, a matching with the SU(3) chiral expansion at NLO is performed.
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    The European physical journal 33 (2004), S. 457-461 
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    Notes: Abstract. A simple higher dimensional mechanism of the doublet-triplet splitting is presented in a five dimensional supersymmetric SU(5) GUT on S 1/Z 2. The splitting of multiplets is realized by a mass term of the Higgs hypermultiplet which explicitly breaks SU(5) gauge symmetry. Depending on the sign of the mass, zero mode Higgs doublets and triplets are localized on either side of the fixed points. The mass splitting is realized due to the difference of magnitudes of the overlap with a brane localized or a bulk singlet field. No unnatural fine-tuning of the parameters is needed. The proton stability is ensured by locality - without symmetries.
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    The European physical journal 33 (2004), S. 333-347 
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    Notes: Abstract. The measurement of the pion form factor and, more generally, of the cross section for electron-positron annihilation into hadrons through the radiative return has become an important task for high luminosity colliders such as the $\Phi$ - or B-meson factories. For a detailed understanding and analysis of this reaction, the construction of a Monte Carlo program, PHOKHARA, has been undertaken. Version 2.0 was based on a next-to-leading order (NLO) treatment of the corrections from initial-state radiation (ISR). In the present paper a further extension of PHOKHARA (version 3.0) is described, which incorporates NLO corrections to final-state radiation (FSR). The impact of combined ISR and FSR on various distributions is investigated and methods are presented which will allow the extraction of the form factor, and even give access to inclusive photon emission due to FSR. The dependence of the results on the model for FSR is discussed and the impact of this contribution on the anomalous magnetic moment of the muon is evaluated.
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    The European physical journal 33 (2004), S. 463-476 
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    Notes: Abstract. Triple gauge boson couplings are measured from W-pair events recorded by the OPAL detector at LEP at centre-of-mass energies of 183 - 209 GeV with a total integrated luminosity of 680 pb-1. Only CP-conserving couplings are considered and SU(2) x U(1) relations are used, resulting in four independent couplings, $\kappa_{\gamma}, g^z_1, \lambda_{\gamma}$ and g z 5. Determining each coupling in a separate fit, assuming the other couplings to take their Standard Model values, we obtain $\kappa_{\gamma} = 0.88^{ + 0.09}_{-0.08}$ , g z 1 = 0.987 + 0.034 -0.033, $\lambda_{\gamma} = -0.060^{ + 0.034}_{-0.033}$ and g z 5 = -0.04 + 0.13 -0.12, where the errors include both statistical and systematic uncertainties. Fits are also performed allowing some of the couplings to vary simultaneously. All results are consistent with the Standard Model predictions.
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    The European physical journal 33 (2004), S. 505-509 
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    Notes: Abstract. The latest ${\rm\pi} N$ elastic scattering data are re-analysed to determine the coupling constant g c of the charged pion, using the dispersion relation for the invariant amplitude B (+ ). Depending on the choice of data-base, values $g^2_c/4{\rm\pi} = 13.80$ to 13.65 are obtained with errors of $\pm 0.12$ . The mass difference between charge states of $\Delta (1232)$ is $M^0 -M^{ + + } = 2.0 \pm 0.4$ MeV, close to twice the mass difference between neutron and proton. The difference in widths on resonance is $\Gamma^0 - \Gamma^{ + + } = 3.8 \pm 1.0$ MeV. One may account for a width difference of 4.5 MeV from phase space for decays and the extra channel $\Delta^0 \to \gamma n$ .
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    The European physical journal 34 (2004), S. 267-275 
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    Notes: Abstract. A method to determine the running of $\alpha$ from a measurement of small angle Bhabha scattering is proposed and worked out. The method is suited to high statistics experiments at e + e --colliders which are equipped with luminometers in the appropriate angular region. A new simulation code predicting small angle Bhabha scattering is also presented.
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    The European physical journal 34 (2004), S. 383-392 
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    Notes: Abstract. In the symplectic Lagrangian framework we in a new fashion embed an irreducible massive vector-tensor theory into a gauge invariant system, which has become reducible, by extending the configuration space to include an additional pair of scalar and vector fields, which give the desired Wess-Zumino action. A comparison with the BFT Hamiltonian embedding approach is also given.
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    The European physical journal 34 (2004), S. 335-344 
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    Notes: Abstract. Results of a new analysis of the K + K - photoproduction at two photon energies, $E_\gamma = 4 \mbox{GeV}$ and $5.65 \mbox{GeV}$ , with a particular emphasis on the S-wave production are presented. We show that the proper treatment of all the helicity components of the S- and P-waves enables one to eliminate the reported discrepancies in the extraction of the S-wave photoproduction cross section from the experimental data.
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    The European physical journal 34 (2004), S. 393-398 
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    Notes: Abstract. We introduce a master action in non-commutative space, out of which we obtain the action of the non-commutative Maxwell-Chern-Simons theory. Then, we look for the corresponding dual theory at both first and second order in the non-commutative parameter. At the first order, the dual theory happens to be, precisely, the action obtained from the usual commutative self-dual model by generalizing the Chern-Simons term to its non-commutative version, including a cubic term. Since this resulting theory is also equivalent to the non-commutative massive Thirring model in the large fermion mass limit, we remove, as a byproduct, the obstacles arising in the generalization to non-commutative space, and to the first non-trivial order in the non-commutative parameter, of the bosonization in three dimensions. Then, performing calculations at the second order in the non-commutative parameter, we explicitly compute a new dual theory which differs from the non-commutative self-dual model and, further, differs also from other previous results and involves a very simple expression in terms of ordinary fields. In addition, a remarkable feature of our results is that the dual theory is local, unlike what happens in the non-Abelian, but commutative case. We also conclude that the generalization to non-commutative space of bosonization in three dimensions is possible only when considering the first non-trivial corrections over ordinary space.
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    The European physical journal 34 (2004), S. 377-381 
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    Notes: Abstract. We discuss the evolution of the fluctuations in a symmetric $\phi_{\mathrm {c}}$ -exponential potential which provides a power-law expansion during inflation using both the gauge-invariant field $\Phi$ and the Sasaki-Mukhanov field.
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    The European physical journal 34 (2004), S. 513-521 
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    Notes: Abstract. The multidimensional space-time with (D-4) compact extra space dimensions and SM fields confined on a four-dimensional brane is considered. The elastic scattering amplitude of two particles interacting by gravitational forces is calculated at superplanckian energies. Particular attention is paid to a proper account of zero (massless) graviton mode. The renormalized Born pole is reproduced in the eikonal amplitude which makes a leading contribution at small momentum transfers. This singular part of the amplitude coincides with well-known D-dimensional amplitude taken at $D \rightarrow 4$ . The expression for the contribution from massive graviton modes to the eikonal is derived, and its asymptotics in the impact parameter is calculated. Our formula gives the correct four-dimensional expression at $R_{\mathrm {c}} \rightarrow 0$ , where R c is the radius of the higher dimensions. The results are also compared with those obtained previously for the scattering of the bulk fields in flat extra dimensions.
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    The European physical journal 34 (2004), S. 447-475 
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    Notes: Abstract. Inspired by recent developments of moose models, we reconsider low-energy effective theories of Goldstone bosons, gauge fields and chiral fermions applied to low-energy QCD and to Higgs-less electroweak symmetry breaking. Couplings and the corresponding reduction of symmetry are introduced via constraints enforced by a set of non-propagating covariantly constant spurion fields. Relics of the latter are used as small expansion parameters conjointly with the usual low-energy expansion. Certain couplings can only appear at higher orders of the spurion expansion and, consequently, they become naturally suppressed independently of the idea of dimensional deconstruction. At leading order this leads to a set of generalized Weinberg sum rules and to the suppression of non-standard couplings to fermions in Higgs-less EWSB models with the minimal particle content. Within the latter, higher spurion terms allow for a fermion mass matrix with the standard CKM structure and C P violation. In addition, Majorana masses for neutrinos are possible. Examples of non-minimal models are briefly mentioned.
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    The European physical journal 34 (2004), S. 477-486 
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    Notes: Abstract. Renormalized triple gauge vertices (TGV) are examined within the two-Higgs-doublet model of the electroweak interactions. Deviations of the TGV from their standard-model values are calculated at the one-loop level, in the on-shell renormalization scheme. As a consistency check, UV divergence cancellations anticipated on symmetry grounds are verified explicitly. The dependence of the TGV finite parts on the masses of possible heavy Higgs scalars is discussed briefly.
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    The European physical journal 34 (2004), S. 435-437 
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    Notes: Abstract. We discuss the quantum state structure using the standard model for three colored quarks in the fundamental representations of SU(3) c making up the singlet ground state of the hadrons. This allows us to calculate a finite von Neumann entropy from the quantum reduced density matrix, which we explicitly evaluate for the quarks in a model for the meson and baryon states.
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    The European physical journal 34 (2004), S. 487-512 
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    Notes: Abstract. High-precision analyses are presented for the production of scalar sleptons, selectrons and smuons in supersymmetric theories, at future e + e - and e - e - linear colliders. Threshold production can be exploited for measurements of the selectron and smuon masses, an essential ingredient for the reconstruction of the fundamental supersymmetric theory at high scales. The production of selectrons in the continuum will allow us to determine the Yukawa couplings in the selectron sector, scrutinizing the identity of the Yukawa and gauge couplings, which is a basic consequence of supersymmetry. The theoretical predictions are elaborated at the one-loop level in the continuum, while at threshold non-zero width effects and Sommerfeld rescattering corrections are included. The phenomenological analyses are performed for e + e - and e - e - linear colliders with energy up to about 1 TeV and with high integrated luminosity up to 1 ab-1 to cover the individual slepton channels separately with high precision.
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    The European physical journal 34 (2004), S. 399-418 
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    Notes: Abstract. A search for pair-produced charged Higgs bosons was performed in the data collected by the DELPHI detector at LEP II at centre-of-mass energies from 189 GeV to 209 GeV. Five different final states, $\tau^ + \nu_{\tau}\tau^- \bar{\nu}_{\tau}$ , $\mathrm{c}\bar{\mathrm{s}}\bar{\mathrm{c}}\mathrm{s}$ , $\mathrm{c}\bar{\mathrm{s}}{\tau^- \bar{\nu}_{\tau}}$ , $\mathrm{W}^*\!\mathrm{A}\mathrm{W}^*\!\mathrm{A}$ and $\mathrm{W}^*\!\mathrm{A}\tau^- \bar{\nu}_{\tau}$ were considered, accounting for the major expected decays in type I and type II Two Higgs Doublet Models. No significant excess of data compared to the expected Standard Model processes was observed. The existence of a charged Higgs boson with mass lower than 76.7 GeV/c 2 (type I) or 74.4 GeV/c 2 (type II) is excluded at the 95% confidence level, for a wide range of the model parameters. Model independent cross-section limits have also been calculated.
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    The European physical journal 34 (2004), S. 429-433 
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    Notes: Abstract. We show the role played by QCD evolution and skewedness effects in the DVCS cross section at large Q 2 within the color dipole description of the process at photon level. The dipole cross section is given by the saturation model, which can be improved by DGLAP evolution at high photon virtualities. We investigate both possibilities as well as the off-forward effect through a simple phenomenological parameterization. The results are compared to the recent ZEUS DVCS data.
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    The European physical journal 34 (2004), S. 419-427 
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    Notes: Abstract. We derive the Feynman rules of the standard model in the axial gauge. After this we prove that the fields $\phi_W$ and $\phi_Z$ do not correspond to physical particles. As a consequence, these fields cannot appear as incoming or outgoing lines in Feynman graphs. We then calculate the contribution of these fields in the case of a particular decay mode of the top quark.
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    The European physical journal 35 (2004), S. 53-65 
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    Notes: Abstract. We present a detailed numerical study of the K e3 decays to ${\cal O}(p^6, (m_d-m_u)p^2, e^2 p^2)$ in chiral perturbation theory with virtual photons and leptons. We describe the extraction of the CKM matrix element |V us | from the experimental K e3 decay parameters. We propose a consistency check of the K + e3 and K 0 e3 data that is largely insensitive to the dominating theoretical uncertainties, in particular the contributions of ${\cal O}(p^6)$ . Our analysis is highly relevant in view of the recent high statistics measurement of the K + e3 branching ratio by E865 at Brookhaven which does not indicate any significant deviation from CKM unitarity but rather a discrepancy with the present K 0 e3 data.
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    The European physical journal 35 (2004), S. 105-118 
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    Notes: Abstract. We present a systematic method for reducing an arbitrary one-loop N-point massless Feynman integral with generic 4-dimensional momenta to a set comprised of eight fundamental scalar integrals: six box integrals in D = 6, a triangle integral in D = 4, and a general two-point integral in D space-time dimensions. All the divergences present in the original integral are contained in the general two-point integral and associated coefficients. The problem of vanishing of the kinematic determinants has been solved in an elegant and transparent manner. Being derived with no restrictions regarding the external momenta, the method is completely general and applicable for arbitrary kinematics. In particular, it applies to the integrals in which the set of external momenta contains subsets comprised of two or more collinear momenta, which are unavoidable when calculating one-loop contributions to the hard-scattering amplitude for exclusive hadronic processes at large-momentum transfer in PQCD. The iterative structure makes it easy to implement the formalism in an algebraic computer program.
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    The European physical journal 35 (2004), S. 145-148 
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    Notes: Abstract. Open Wilson lines are known to be the observables of non-commutative gauge theory with Moyal-Weyl *-product. We generalize these objects to more general *-products. As an application we derive a formula for the inverse Seiberg-Witten map for *-products with invertible Poisson structures.
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    The European physical journal 35 (2004), S. 1-20 
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    Notes: Abstract. Approximately 438 pb-1 of e + e- data from the OPAL detector, taken with the LEP collider running at centre-of-mass energies of 192-209 GeV, are analyzed to search for evidence of chargino pair production, ${\mathrm{e}}^ + {\mathrm{e}}^-\to\tilde\chi^ + _1\tilde\chi^-_1$ , or neutralino associated production, ${\mathrm{e}}^ + {\mathrm{e}}^-\to\tilde\chi^0_2\tilde\chi^0_1$ . Limits are set at the 95% confidence level on the product of the cross-section for the process ${\mathrm{e}}^ + {\mathrm{e}}^-\to\tilde\chi^ + _1\tilde\chi^-_1$ and its branching ratios to topologies containing jets and missing energy, or jets with a lepton and missing energy, and on the product of the cross-section for ${\mathrm{e}}^ + {\mathrm{e}}^-\to\tilde\chi^0_2\tilde\chi^0_1$ and its branching ratio to jets. R-parity conservation is assumed throughout this paper. When these results are interpreted in the context of the Constrained Minimal Supersymmetric Standard Model, limits are also set on the masses of the $\tilde\chi^{\pm}_1, \tilde\chi^0_1$ and $\tilde\chi^0_2$ , and regions of the parameter space of the model are ruled out. Nearly model-independent limits are also set at the 95% confidence level on $\sigma({\mathrm{e}}^ + {\mathrm{e}}^-\to\tilde\chi^ + _1\tilde\chi^-_1)$ with the assumption that each chargino decays via a W boson, and on $\sigma({\mathrm{e}}^ + {\mathrm{e}}^-\to\tilde\chi^0_2\tilde\chi^0_1)$ with the $\tilde\chi^0_2$ assumed to decay via a Z0.
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    The European physical journal 35 (2004), S. 35-52 
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    Notes: Abstract. Oscillations in the B 0 s - $\overline{{B}^0_s}$ system were studied in events selected from about 4.3 million hadronic Z0 decays registered by DELPHI between 1992 and 2000. This paper presents updates of two published analyses ([11, 12]). The first analysis, which utilizes leptons emitted with large momentum transverse to a jet, was improved by means of a better algorithm for the vertex reconstuction and a new algorithm for flavour-tagging at production time. The second analysis, which utilizes D s -lepton events, was improved by optimizing the treatment of proper time resolution. No signal of B 0 s oscillations was observed and limits on the mass difference between the physical B 0 s states were obtained to be: $$ \begin{array}{@{}l@{}} \Delta m_s 〉 8.0\, {\mathrm{{ps}^{-1}~at~the~95\%~C.L.}}\\ {\mathrm{with~a~sensitivity~of}}~~\Delta m_s = 9.1\,{\mathrm{ps}^{-1}} \end{array} $$ in the high p t lepton analysis and $$\begin{array}{@{}l@{}} \Delta m_s 〉 4.9\, {\mathrm{{ps}^{-1}~at~the~95\%~C.L.}}\\ {\mathrm{with~a~sensitivity of}}~~\Delta m_s = 8.6\,{\mathrm{ps}}^{-1} \end{array} $$ in the D s -lepton analysis. Previously published results on these analyses are superseded. The combination of these results with those obtained in other independent analyses previously performed in DELPHI (D s -hadron, exclusive B s 0, inclusive vertex) gives: $$ \begin{array}{@{}l@{}} \Delta m_s 〉 8.5\,{\mathrm{{ps}^{-1}~at~the~95\%~C.L.}} \\ {\mathrm{with~a~sensitivity~of}}~~ \Delta m_s = 12.0\,{\mathrm{ps}}^{-1}. \end{array} $$
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    The European physical journal 35 (2004), S. 283-292 
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    Notes: Abstract. A non-local toy model whose interaction consists of smeared, non-local field operators is presented. We work out the Feynman rules and propose a power counting formula for arbitrary graphs. Explicit calculations for one loop graphs show that their contribution is finite for sufficient smearing and agree with the power counting formula. UV/IR mixing does not occur.
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    The European physical journal 35 (2004), S. 177-187 
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    Notes: Abstract. The hadronic annihilation branching-ratios in quasi-two-body final states have been obtained from the observation of the reactions $\bar p p$ $\rightarrow $ $\pi^ + \pi^- \pi^0$ , $K^ + K^- \pi^0,K^\pm \pi^\mp K^0$ at rest in hydrogen targets at different densities. The enhancement or suppression of specific hadronic channels connected to dynamical selection rules is observed in the production of different resonances both in protonium S and P-waves, systematically investigated for the first time. Besides the well known $\rho(770) \pi$ and $a_2(1320) \pi$ enhancement from 3 S 1 and 1 S 0 partial waves, the dominance of one isospin source in $K^*(892) \bar K$ production, well established from S-waves, is confirmed also in P-waves (1 S 0, I = 0; 3 S 1, I = 1; 1 P 1, I = 0; 3 P 1, I = 0; 3 P 2, I = 1). In addition, the experimental data clearly show a strong suppression of $\phi(1020) \pi$ and $a_0(980) \pi$ final states from P-wave which has a remarkable coincidence with $K^*(892) \bar K$ pattern production.
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    The European physical journal 35 (2004), S. 197-206 
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    Notes: Abstract. General expressions for the double-lepton polarizations in the $B \to K \ell^ + \ell^-$ decay are obtained, using a model independent effective Hamiltonian, including all possible interactions. Correlations between the averaged double-lepton polarization asymmetries and the branching ratio, as well as the averaged single-lepton polarization asymmetry are studied. It is observed that a study of the double-lepton polarization asymmetries can serve as a good test for establishing new physics beyond the standard model.
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    The European physical journal 35 (2004), S. 159-170 
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    Notes: Abstract. Tau-pair production in the process $\ensuremath{\mathrm{e}^ + \mathrm{e}^- \rightarrow \mathrm{e}^ + \mathrm{e}^-\tau^ + \tau^-}$ was studied using data collected by the DELPHI experiment at LEP2 during the years 1997 - 2000. The corresponding integrated luminosity is 650 pb-1. The values of the cross-section obtained are found to be in agreement with QED predictions. Limits on the anomalous magnetic and electric dipole moments of the tau lepton are deduced.
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    The European physical journal 35 (2004), S. 383-392 
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    Notes: Abstract. We work with $\phi^4$ theory and study the 4PI effective action at 3-loop order. We discuss the relation between the equations of motion obtained by taking functional derivatives of the effective action with respect to the variational parameters, and the Schwinger-Dyson (SD) equations. We show that the equation obtained by differentiating with respect to the connected 2-point function is identical to the SD equation for the truncated 2-point function; differentiating with respect to the connected 3-point function reproduces the SD equation for the truncated 3-point function, up to 1-loop order; and differentiating with respect to the connected 4-point function reproduces the SD equation for the truncated 4-point function, at the tree level. These results establish a connection between two techniques for performing non-equilibrium calculations, and provide a starting place for a study of the gauge dependence of quantities derived from an nPI effective action.
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    The European physical journal 35 (2004), S. 349-357 
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    Notes: Abstract. By using the non-relativistic effective Lagrangian approach to bound states, a complete expression for the isospin-breaking corrections to the energy levels and the decay widths of kaonic hydrogen is obtained up-to-and-including $O(\alpha,m_d-m_u)$ in QCD. It is demonstrated that, although the leading-order corrections at $O(\alpha^{1/2},(m_d-m_u)^{1/2})$ emerging due to the unitarity cusp are huge, they can be expressed solely in terms of the KN S-wave scattering lengths. Consequently, at leading order, it is possible to derive parameter-free modified Deser-type relations, which can be used to extract the scattering lengths from the hadronic atom data.
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    The European physical journal 35 (2004), S. 313-324 
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    Notes: Abstract. Higgs boson production with subsequent decay to photons was searched for in the data collected by the DELPHI detector at centre-of-mass energies between 183 GeV and 209 GeV, corresponding to a total integrated luminosity of nearly 650 pb-1. No evidence for a signal was found, and limits were set on h 0 Z 0 and h 0 A 0 production with h 0 decay to photons. These results were used to exclude regions in the parameter space of fermiophobic scenarios of Two Higgs Doublet Models.
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    The European physical journal 35 (2004), S. 567-577 
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    Notes: Abstract. This paper shows that the properties of space-time that constitutes the background of the theory of special relativity, namely its dimensionality, the correct partition of dimensions between one time-type and three space-type dimensions and the Minkowski metrics, may emerge from a set of completely interacting binary units structured by a noise defined in a Landau-type free energy of Higgs fields and by gauge symmetries, in particular those related to the permutation group of four objects.
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    The European physical journal 35 (2004), S. 437-455 
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    Notes: Abstract. Tau lepton decays with open strangeness in the final state are measured with the OPAL detector at LEP to determine the strange hadronic spectral function of the $\tau$ lepton. The decays $\tau^{-}\rightarrow(K\pi)^{-}\nu_{\tau}$ , $(\pi\pi)^{-}\nu_{\tau}$ and $(K\pi\pi\pi)^{-}\nu_{\tau}$ with final states consisting of neutral and charged kaons and pions have been studied. The invariant mass distributions of $93.4\%$ of these final states have been experimentally determined. Monte Carlo simulations have been used for the remaining $6.6\%$ and for the strange final states including $\eta$ mesons. The reconstructed strange final states, corrected for resolution effects and detection efficiencies, yield the strange spectral function of the $\tau$ lepton. The moments of the spectral function and the ratio of strange to non-strange moments, which are important input parameters for theoretical analyses, are determined. Furthermore, the branching fractions $B(\tau^{-}\rightarrow K^{-}\pi^{0}\nu_{\tau}) = (0.471\pm0.059_{\mathrm{stat}}\pm0.023_{\mathrm{sys}})\%$ and $B(\tau^{-}\rightarrow K^{-}\pi^{ + }\pi^{-}\nu_{\tau}) = (0.415\pm0.053_{\mathrm{stat}}\pm0.040_{\mathrm{sys}})\%$ have been measured.
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    The European physical journal 35 (2004), S. 457-486 
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    Notes: Abstract. The hadronic final states observed with the ALEPH detector at LEP in ${\rm e}^ + {\rm e}^-$ annihilation are analysed using 730 pb-1 of data collected between 91 and 209 GeV in the framework of QCD. In particular event-shape variables and inclusive charged particle spectra are measured. The energy evolution of quantities derived from these measurements is compared to analytic QCD predictions. The mean charged particle multiplicity, the charged particle momentum spectrum and its peak position are compared to predictions of the modified-leading-logarithmic approximation. The strong coupling constant $\alpha_s$ is determined from a fit of the QCD prediction to distributions of six event-shape variables at eight centre-of-mass energies. A study of non-perturbative power law corrections is presented.
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    The European physical journal 36 (2004), S. 37-42 
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    Notes: Abstract. We review different definitions of the $\epsilon'$ parameter describing direct CP-violation in neutral kaon decays, which was precisely measured in recent experiments, and point out the inconsistency of some of them due to a CPT-constraint. The proper comparison of the experimental results to the theoretical computations is discussed.
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    The European physical journal 36 (2004), S. 89-95 
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    Notes: Abstract. We discuss the time-dependent CP asymmetry of the decay $B \rightarrow \phi K_{\mathrm {S}}$ in an extension of the standard model with both a two Higgs doublet and additional fourth-generation quarks. We show that, although the standard model with a two Higgs doublet and the standard model with fourth-generation quarks alone are not likely to largely change the effective $\sin 2 \beta$ from the decay $B \rightarrow \phi K_{\mathrm {S}}$ , the model with both an additional Higgs doublet and fourth-generation quarks can easily account for the possible large negative value of $\sin 2 \beta$ without conflicting with other experimental constraints. In this model, additional large CP violating effects may arise from the flavor-changing Yukawa interactions between neutral Higgs bosons and the heavy fourth-generation down type quark, which can modify the QCD penguin contributions. With the constraints obtained from $b \rightarrow s \bar{s} s$ processes such as $B \rightarrow X_{s} \gamma$ and $\Delta m_{B_{s}^{0}}$ , this model can lead to an effective $\sin 2 \beta$ as large as - 0.4 in the CP asymmetry of ${B \rightarrow \phi K_{\mathrm {S}}}$ .
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    The European physical journal 36 (2004), S. 25-36 
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    Notes: Abstract. We study the electrodynamic process in which a photon is emitted together with an e --e + pair in the presence of a strong slowly rotating magnetic field. In particular, the spectrum of photons produced in this way is calculated starting from an effective Lagrangian that allows at tree level for the process itself. The magnetic field strengths we have in mind are $\sim 10^{14} \mathrm{G}$ in such a way that, although our model is an oversimplified version of the real physical situation, the results can be applied only in some particular astrophysical scenarios (magnetars, massive black holes).
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    The European physical journal 36 (2004), S. 43-48 
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    Notes: Abstract. The large t behavior of the helicity amplitudes of diffractive photoproduction is estimated relying on models of the photon and meson light-cone wave functions and on the double-logarithmic approximation to the exchanged gluon interaction. The role of large-size color dipole contributions to the photon-meson transition impact factor is discussed.
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    The European physical journal 36 (2004), S. 1-23 
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    Notes: Abstract. Searches for pair-production of supersymmetric particles under the assumption of non-conservation of R-parity with a dominant LL $\bar{\rm E}$ or ${\rm\bar{U}\bar{D}\bar{D}}$ term have been performed using the data collected by the DELPHI experiment at LEP in e + e- collisions at centre-of-mass energies from 192 up to 208 GeV. No excess of data above Standard Model expectations was observed. The results were used to constrain the MSSM parameter space and to derive limits on the masses of supersymmetric particles.
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    The European physical journal 36 (2004), S. 103-111 
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    Notes: Abstract. We present the results on non-perturbative quantum gravity effects related to extra dimensions which can be comparable, in some cases, with the SM contributions, e.g. in lepton-lepton or lepton-nucleon scattering. The case of cosmic neutrino gravitational interaction with atmospheric nucleons is considered in detail.
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    The European physical journal 36 (2004), S. 79-87 
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    Notes: Abstract. We consider a model with a charged vector field along with a Cremmer-Scherk-Kalb-Ramond (CSKR) matter field coupled to a U(1) gauge potential. We obtain a natural Lorentz symmetry violation due to the local U(1) spontaneous symmetry breaking mechanism triggered by the imaginary part of the vector matter. The choice of the unitary gauge leads to the decoupling of the gauge-KR sector from the Higgs-KR sector. The excitation spectrum is carefully analyzed and the physical modes are identified. We propose an identification of the neutral massive spin-1 Higgs-like field with the massive Z’ boson of the so-called mirror matter models.
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    The European physical journal 36 (2004), S. 113-116 
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    Notes: Abstract. Following Wong’s approach to formulating the classical dynamics of charged particles in non-Abelian gauge theories, we derive the classical equations of motion of a charged particle in U(1) gauge theory on non-commutative space, the so-called non-commutative QED. In the present use of the procedure, it is observed that the definition of the mechanical momenta should be modified. The derived equations of motion manifest the previous statement about the dipole behavior of the charges in non-commutative space.
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    The European physical journal 36 (2004), S. 147-159 
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    Notes: Abstract. Bose-Einstein correlations are studied in pairs of charged pions from hadronic Z decays, collected by the ALEPH detector. The correlation function, measured using either the unlike-sign or the mixed reference sample, is studied in terms of the Lorentz-invariant four-momentum difference and its transverse, Q T, and longitudinal, Q L, components with respect to the longitudinal centre-of-mass system. Values for the correlation radii, R T and R L, are obtained from the fit of the Goldhaber parametrisation. The results indicate that the correlation radii values depend on the chosen kind of reference sample and on the two-jet purity.
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    The European physical journal 36 (2004), S. 169-175 
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    Notes: Abstract. Using a four dimensional approach, we show that the singularities for small gluon momenta, which arise in the usual three dimensional treatment of the annihilation decay, disappear if all poles in the relative energy are taken into account correctly in the integration. We obtain an explicit formula for the decay width which involves a non-locality originating from the kinetic energy. We calculate not only the familiar logarithmic dependence on the binding energy, but also the constant to be added to the logarithm. The logarithmic term agrees with previous values in the literature. In QCD the constant turns out to be quite small, but only because there is an almost perfect cancellation between the tree graph and a non-abelian loop graph which contributes to the decay amplitude to the same order.
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    The European physical journal 36 (2004), S. 201-213 
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    Notes: Abstract. We calculate threshold soft-gluon corrections to total cross sections and transverse momentum distributions for bottom and charm quark production in fixed target experiments, considering both pp and $\pi^- p$ interactions. We investigate the quality of the near-threshold soft-gluon approximation at next-to-leading order (NLO) and calculate next-to-next-to-leading order (NNLO) corrections through next-to-next-to-next-to-leading-logarithmic (NNNLL) accuracy, including some virtual terms. We find that the NNLO threshold corrections reduce the factorization and renormalization scale dependence of the cross sections.
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    The European physical journal 36 (2004), S. 221-226 
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    Notes: Abstract. The formation of Hückel-Debye screening in a $q\bar{q}$ plasma is studied following as close as possible the procedures used in the usual electric case. The equivalent of the Debye length is found, but the screening as a result is found to be less efficient than for the Coulomb interaction, since the correlation functions decay as the exponential of the distance raised at a power less than one.
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    The European physical journal 36 (2004), S. 233-243 
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    Notes: Abstract. We study CP-sensitive observables in the neutralino production $e^ + e^-\to\tilde\chi^0_i \tilde\chi^0_j$ and the subsequent two-body decays of the neutralino $\tilde\chi^0_i \to \chi^0_n Z$ and of the Z boson $Z \to \ell \bar\ell (q\bar q)$ . We identify the CP-odd elements of the Z boson density matrix and propose CP-sensitive triple-product asymmetries. We calculate these observables and the cross sections in the minimal supersymmetric standard model with complex parameters μ and M 1 for an e + e - linear collider with $\sqrt{s} = 800$ GeV and longitudinally polarized beams. We show that the asymmetries can reach $3\%$ for $Z \to \ell \bar\ell $ and $18\%$ for $Z \to q\bar q$ and discuss the feasibility of measuring these asymmetries.
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    The European physical journal 36 (2004), S. 227-232 
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    Notes: Abstract. We show that it is possible to enforce texture zeros in arbitrary entries of the fermion mass matrices by means of Abelian symmetries; in this way, many popular mass-matrix textures find a symmetry justification. We propose two alternative methods which allow one to place zeros in any number of elements of the mass matrices that one wants. They are applicable simultaneously in the quark and lepton sectors. They are also applicable in grand unified theories. The number of scalar fields required by our methods may be large; still, in many interesting cases this number can be reduced considerably. The larger the desired number of texture zeros is, the simpler are the models which reproduce the texture.
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    The European physical journal 36 (2004), S. 161-168 
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    Notes: Abstract. A partial wave analysis of PS185 data for $\bar pp \to \bar \Lambda \Lambda$ is presented. A 3 S 1 cusp is identified in the inverse process $\bar \Lambda \Lambda \to \bar p p$ at threshold, using detailed balance to deduce cross sections from $\bar pp \to \bar \Lambda \Lambda$ . Partial wave amplitudes for $\bar pp$ 3 P 0, 3 F 3, 3 D 3 and 3 G 3 exhibit a behaviour very similar to resonances observed in Crystal Barrel data. With this identification, the $\bar pp \to \bar \Lambda \Lambda$ data then provide evidence for a new I = 0, J PC = 1- resonance with mass $M = 2290 \pm 20$ MeV, $\Gamma = 275 \pm 35$ MeV, coupling to both 3 S 1 and 3 D 1.
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    The European physical journal 36 (2004), S. 365-370 
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    Notes: Abstract. We study the exclusive decays of the B meson into pseudoscalar charmonium states $\eta_c$ and $\eta_c^\prime$ within the QCD factorization approach and find that the non-factorizable corrections to naive factorization are infrared safe at leading-twist order. The spectator interactions arising from the kaon twist-3 effects are formally power suppressed but chirally and logarithmically enhanced. An important improvement by including the $\mathcal{O}(\alpha_{\mathrm{s}})$ corrections is the cancellation of the renormalization scale μ dependence of the decay amplitude. However, the calculated decay rates are too small to accommodate the experimental data. On the other hand, we compare the theoretical calculations for B meson decays to $J/\psi, \psi^\prime, \eta_c$ and $\eta_c^\prime$ , and find that the predicted relative decay rates of these four states are approximately compatible with the experimental data.
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    The European physical journal 36 (2004), S. 283-296 
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    Notes: Abstract. The tau lepton lifetime has been measured with the ${\rm e}^ + {\rm e}^- \rightarrow {\rm\tau}^ + {\rm\tau}^-$ events collected by the DELPHI detector at LEP in the years 1991-1995. Three different methods have been exploited, using both one-prong and three-prong $\tau$ decay channels. Two measurements have been made using events in which both taus decay to a single charged particle. Combining these measurements gave $\tau_\tau \mbox{(1 prong)} = 291.8\pm 2.3_{\mathrm{stat}} \pm 1.5_{\mathrm{sys}} \mathrm{fs}$ . A third measurement using taus which decayed to three charged particles yielded $\tau_\tau \mbox{(3 prong)} = 288.6\pm 2.4_{\mathrm{stat}} \pm 1.3_{\mathrm{sys}} \mathrm{fs}. $ These were combined with previous DELPHI results to measure the tau lifetime, using the full LEP1 data sample, to be $\tau_\tau = 290.9\pm 1.4_{\mathrm{stat}} \pm 1.0_{\mathrm{sys}} \mathrm{fs}$ .
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    The European physical journal 33 (2004), S. 511-521 
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    Notes: Abstract. The rates of inclusive photo- and electroproduction of the $\eta_c$ meson: $\gamma(^*) + p \to \eta_c + X$ are calculated in the triple Regge region, integrated over the diffractive mass X. For the Regge exchanges we use the hard pomeron and odderon, both being calculated in the framework of perturbative QCD. The integrated cross section depends upon the coupling of the BFKL pomeron to two C = -1 odderons, and it is found to be of the order of 60 pb for photoproduction and 1.5 pb at Q 2 = 25 GeV2.
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    The European physical journal 34 (2004), S. 57-60 
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    The European physical journal 34 (2004), S. 85-90 
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    Springer
    The European physical journal 36 (2004), S. 503-507 
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. We study the possibility of observing an “invisible” Higgs boson in central exclusive diffractive production at the LHC. We evaluate the cross section using, as a simple example, the standard model with a heavy fourth generation, where the invisible decay mode $H \to \nu_4 \bar{\nu}_4$ dominates, with the heavy neutrino mass $M(\nu_4) \simeq 50$ GeV. We discuss the possible requirements on trigger conditions and the background processes.
    Type of Medium: Electronic Resource
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    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 36 (2004), S. 515-522 
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. We consider the process $e^ + e^-\to\tilde{\chi}^ + _i\tilde{\chi}^-_j$ at a linear collider with transverse $e^{\pm}$ beam polarization. We investigate the influence of the CP phases on azimuthal asymmetries in $e^ + e^-\to\tilde{\chi}^ + _i\tilde{\chi}^-_j$ with subsequent two-body decays $\tilde{\chi}^-_j\to \tilde{\nu}_{\ell}\ell^-$ and $\tilde{\chi}^-_j\to W^-\tilde{\chi}^0_1$ . We show that triple product correlations involving the transverse $e^{\pm}$ beam polarization vanish if at least one subsequent chargino decay is not observed. We derive this result within the minimal supersymmetric standard model (MSSM) with complex parameters; however, it holds also in the general MSSM with SUSY flavor violation.
    Type of Medium: Electronic Resource
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