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  • Articles  (188,517)
  • Other Sources  (339)
  • Springer  (173,862)
  • National Academy of Sciences  (14,994)
  • MDPI Publishing
  • 2000-2004  (188,856)
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  • Books  (4)
  • Articles  (188,517)
  • Other Sources  (339)
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  • 1
    Electronic Resource
    Electronic Resource
    The identification of LDA seeding particles by the phase-Doppler technique (2004)
    Springer
    Experiments in fluids 6 (2004), S. 137-140 
    Details
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00196466
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  • 2
    Electronic Resource
    Electronic Resource
    Selective control of flow coherence in triangular jets (2004)
    Springer
    Experiments in fluids 6 (2004), S. 129-135 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00196464
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  • 3
    Electronic Resource
    Electronic Resource
    Thermofluiddynamic experiments with a heated and rotating circular cylinder in crossflow (2004)
    Springer
    Experiments in fluids 6 (2004), S. 111-114 
    Details
    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 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00196461
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  • 4
    Electronic Resource
    Electronic Resource
    Double pulsed particle image velocimeter with directional resolution for complex flows (2004)
    Springer
    Experiments in fluids 6 (2004), S. 119-128 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00196463
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  • 5
    Electronic Resource
    Electronic Resource
    Time dependent flow visualization in the separated region of an appendage-flat plate junction (2004)
    Springer
    Experiments in fluids 6 (2004), S. 140-143 
    Details
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00196467
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  • 6
    Electronic Resource
    Electronic Resource
    Laser Doppler velocity bias in separated turbulent flows (2004)
    Springer
    Experiments in fluids 6 (2004), S. 80-88 
    Details
    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 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00196457
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  • 7
    Electronic Resource
    Electronic Resource
    Computer-aided calibration of X-probes using a look-up table (2004)
    Springer
    Experiments in fluids 6 (2004), S. 115-118 
    Details
    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 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00196462
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  • 8
    Electronic Resource
    Electronic Resource
    Evaporation of single liquid drops in an immiscible liquid at elevated pressures: equipment and preliminary results (2004)
    Springer
    Experiments in fluids 6 (2004), S. 73-79 
    Details
    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 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00196456
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  • 9
    Electronic Resource
    Electronic Resource
    Turbulent dispersion of droplets for air flow in a pipe (2004)
    Springer
    Experiments in fluids 6 (2004), S. 94-104 
    Details
    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 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00196459
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  • 10
    Electronic Resource
    Electronic Resource
    Speckle photographic measurement of turbulence in an air stream with fluctuating temperature (2004)
    Springer
    Experiments in fluids 6 (2004), S. 89-93 
    Details
    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 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00196458
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  • 11
    Electronic Resource
    Electronic Resource
    A similar profile for the tangential velocity in vortex chambers (2004)
    Springer
    Experiments in fluids 6 (2004), S. 135-137 
    Details
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00196465
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  • 12
    Electronic Resource
    Electronic Resource
    Announcements (2004)
    Springer
    Experiments in fluids 6 (2004), S. 144-144 
    Details
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00196468
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  • 13
    Electronic Resource
    Electronic Resource
    Determination of the measuring position in laser-Doppler anemometry (2004)
    Springer
    Experiments in fluids 6 (2004), S. 105-110 
    Details
    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 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00196460
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  • 14
    Electronic Resource
    Electronic Resource
    Lepton flavor violating Z-decays in supersymmetric seesaw model (2004)
    Springer
    The European physical journal 32 (2004), S. 245-252 
    Details
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. In the supersymmetric seesaw model, large flavor mixings of sleptons induce the lepton flavor violating (LFV) interactions $\ell_I \bar\ell_J V$ ( $V = \gamma, Z$ ), which give rise to various LFV processes. In this work we examine the LFV decays $Z\to\ell_I \bar\ell_J$ . Subject to the constraints from the existing neutrino oscillation data and the experimental bounds on the decays $\ell_J\to\ell_I\gamma$ , these LFV Z-decays are found to be sizable, and among them the largest-rate channel $Z\to \tau \bar{\mu}$ can occur with a branching ratio of 10-8 and may be accessible at the LHC or GigaZ experiment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1140/epjc/s2003-01391-1
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  • 15
    Electronic Resource
    Electronic Resource
    $\mbox{Log}(1/x)$ gluon distribution and structure functionsin the loop-loop correlation model (2004)
    Springer
    The European physical journal 33 (2004), S. 63-74 
    Details
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. We consider the interaction of the partonic fluctuation of a scalar “photon” with an external color field to calculate the leading and next-to-leading order gluon distribution of the proton following the work done by Dosch-Hebecker-Metz-Pirner. We relate these gluon distributions to the short and long distance behavior of the cross section of an adjoint dipole scattering off a proton. The leading order result is a constant, while the next-to-leading order result shows a $\ln(1/x)$ enhancement at small x. To get numerical results for the gluon distributions at the initial scale Q 2 0 = 1.8 GeV2, we compute the adjoint dipole-proton cross section in the loop-loop correlation model. Quark distributions at the same initial scale are parameterized according to Regge theory. We evolve quark and gluon distributions to higher Q 2 values using the DGLAP equation and compute charm and proton structure functions in the small-x region for different Q 2 values.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1140/epjc/s2003-01528-2
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  • 16
    Electronic Resource
    Electronic Resource
    Symmetry breaking of the symmetric left-right model without a scalar bidoublet (2004)
    Springer
    The European physical journal 32 (2004), S. 555-559 
    Details
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. By invoking the existence of a general O(2) symmetry, a minimal left-right symmetric model based on the gauge group $G = SU(2)_{\mathrm {L}}\otimes SU(2)_{\mathrm {R}}\otimes U(1)_{B-L}$ is shown to require the existence of only two physical Higgs bosons. The lighter Higgs is predicted to have a small mass which could be evaluated by standard perturbation theory. The fermionic mass matrices are recovered by insertion of ad hoc fermion-Higgs interactions. The model is shown to be undistinguishable from the standard model at the currently reachable energies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1140/epjc/s2003-01442-7
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  • 17
    Electronic Resource
    Electronic Resource
    Quantum-hydrodynamical picture of the massive Higgs boson (2004)
    Springer
    The European physical journal 33 (2004), S. 297-305 
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    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. The phenomenon of spontaneous symmetry breaking admits a physical interpretation in terms of the Bose condensation process of elementary spinless quanta. In this picture, the broken-symmetry phase emerges as a real physical medium, endowed with a hierarchical pattern of scales, supporting two types of elementary excitations for ${\vec{k}} \to 0$ : a massive energy branch $E_a({\vec{k}}) \to M_H$ , corresponding to the usual Higgs boson field, and a collective gapless branch $E_b({\vec{k}}) \to 0$ . This is similar to the coexistence of phonons and rotons in superfluid 4He that, in fact, is usually considered the condensed-matter analog of the Higgs condensate. After previous work dedicated to the properties of the gapless phonon branch, in this paper we use quantum hydrodynamics to propose a physical interpretation of the massive branch. On the base of our results, M H coincides with the energy gap for vortex formation and a massive Higgs boson is like a roton in superfluid 4He. Within this interpretation of the Higgs particle, there is no naturalness problem since M H remains a naturally intermediate, fixed energy scale, even for an ultimate ultraviolet cutoff $\Lambda\to \infty$ .
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1140/epjc/s2003-01567-7
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  • 18
    Electronic Resource
    Electronic Resource
    Measurement of the μ decay spectrum with the ICARUS liquid Argon TPC (2004)
    Springer
    The European physical journal 33 (2004), S. 233-241 
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    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. Examples are given which prove the ICARUS detector quality through relevant physics measurements. We study the μ decay energy spectrum from a sample of stopping μ events acquired during the test run of the ICARUS T600 detector. This detector allows the spatial reconstruction of the events with fine granularity, hence, the precise measurement of the range and dE/dx of the μ with high sampling rate. This information is used to compute the calibration factors needed for the full calorimetric reconstruction of the events. The Michel $\rho$ parameter is then measured by comparison of the experimental and Monte Carlo simulated μ decay spectra, obtaining $\rho = 0.72\pm 0.06 \textrm{(stat.)} \pm 0.08 \textrm{(syst.)}$ . The energy resolution for electrons below $\sim 50$ MeV is finally extracted from the simulated sample, obtaining $(E^e_{\textrm{meas}}-E^e_{\text{MC}})/E^e_{MC} = 11\% /\sqrt{E\textrm{[MeV]}} \oplus 2\%$ .
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1140/epjc/s2004-01597-7
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  • 19
    Electronic Resource
    Electronic Resource
    Effects of the scalar FCNC in $b\rightarrow sl^ + l^-$ transitions and supersymmetry (2004)
    Springer
    The European physical journal 33 (2004), S. 123-136 
    Details
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1140/epjc/s2003-01525-5
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  • 20
    Electronic Resource
    Electronic Resource
    Classification and asymptotic scaling of the light-cone wave-function amplitudes of hadrons (2004)
    Springer
    The European physical journal 33 (2004), S. 75-90 
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    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. We classify the hadron light-cone wave-function amplitudes in terms of parton helicity, orbital angular momentum, and quark-flavor and color symmetries. We show in detail how this is done for the pion, $\rho$ meson, nucleon, and delta resonance up to and including three partons. For the pion and nucleon, we also consider four-parton amplitudes. Using the scaling law derived previously, we show how these amplitudes scale in the limit that all parton transverse momenta become large.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1140/epjc/s2003-01563-y
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  • 21
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    Exclusive $B \to (K^*, \rho) \gamma$ decays in general two-Higgs-doublet models (2004)
    Springer
    The European physical journal 33 (2004), S. 349-368 
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    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. By employing the QCD factorization approach, we calculated the next-to-leading order new physics contributions to the branching ratios, CP asymmetries, isospin and U-spin symmetry breaking of the exclusive decays $B \to V \gamma$ ( $V = K^*, \rho$ ), induced by the charged Higgs penguins in general two-Higgs-doublet models. Within the considered parameter space, we found that (a) the new physics corrections to the observables are generally small in model I and model III-A, moderate in model II, but large in model III-B; (b) from the well measured branching ratios and upper limits, a lower bound of M H 〉 200 GeV in model II was obtained, while the allowed range of M H in model III-B is $ 226 \leq M_{H} \leq 293 $ GeV; these bounds are comparable with those from the inclusive $B \to X_s \gamma$ decay; (c) the NLO Wilson coefficient C 7(m b ) in model III-B is positive and disfavored by the measured value of isospin symmetry breaking $ \Delta_{0-}^{\mathrm{{exp}}} (K^*\gamma) = (3.9 \pm 4.8)\%$ , but it still cannot be excluded if we take the large errors into account; (d) the CP asymmetry $\mathcal{A}_{CP}(B \to \rho \gamma)$ in model III-B has an opposite sign to the one in the standard model (SM), which may be used as a good observable to distinguish the SM from model III-B; (e) the isospin symmetry breaking $ \Delta(\rho\gamma)$ is less than $10\%$ in the region of $\gamma = [ 40 \sim 70]^\circ$ preferred by the global fit result, but it can be as large as 20 to $40\%$ in the regions of $\gamma \leq 10^\circ$ and $\gamma \geq 120^\circ$ . The SM and model III-B predictions for $ \Delta(\rho\gamma)$ are opposite in sign for small or large values of the CKM angles; (f) the U-spin symmetry breaking $\Delta U(K^*,\rho)$ in the SM and the general two-Higgs-doublet models is generally small in size: $\sim 10^{-7}$ .
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    URL: http://dx.doi.org/10.1140/epjc/s2004-01592-0
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  • 22
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    Signatures of the handbag mechanism in wide-angle photoproduction of pseudoscalar mesons (2004)
    Springer
    The European physical journal 33 (2004), S. 91-103 
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    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. Wide-angle photoproduction of pseudoscalar mesons is investigated under the assumption of dominance of the handbag mechanism, considering both quark helicity flip and non-flip. The partonic subprocess, meson photoproduction off quarks, is analysed with the help of a covariant decomposition of the subprocess amplitudes which is independent of a specific meson generation mechanism. As examples of subprocess dynamics, however, the twist-2 as well as two-particle twist-3 contributions are explicitly calculated. Characteristic features of the handbag approach are discussed in dependence upon the relative magnitudes of the invariant functions. Differential cross sections and spin correlations are predicted to show a characteristic behaviour which allows one to test the underlying assumption of handbag dominance.
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    URL: http://dx.doi.org/10.1140/epjc/s2003-01576-6
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  • 23
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    Search for single top quark production in ep collisions at HERA (2004)
    Springer
    The European physical journal 33 (2004), S. 9-22 
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    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. A search for single top quark production is performed in $e^{\pm}p$ collisions at HERA. The search exploits data corresponding to an integrated luminosity of 118.3 pb-1. A model for the anomalous production of top quarks in a flavour changing neutral current process involving a $tu\gamma$ coupling is investigated. Decays of top quarks into a b quark and a W boson are considered in the leptonic and the hadronic decay channels of the W. Both a cut-based analysis and a multivariate likelihood analysis are performed to discriminate anomalous top quark production from Standard Model background processes. In the leptonic channel, 5 events are found while 1.31 $\pm$ 0.22 events are expected from the Standard Model background. In the hadronic channel, no excess above the expectation for Standard Model processes is found. These observations lead to a cross section $\sigma (ep \rightarrow e t X) = 0.29 ^{ + 0.15}_{-0.14} \ {\rm pb}$ at $\sqrt{s} = 319 \ {\rm GeV}$ . Alternatively, assuming that the observed events are due to a statistical fluctuation, upper limits of 0.55 pb on the anomalous top production cross section and of 0.27 on the $tu\gamma$ coupling $\kappa_{tu\gamma}$ are established at the 95% confidence level.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1140/epjc/s2003-01588-2
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  • 24
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    Extending the study of the Higgs sector at the LHC by proton tagging (2004)
    Springer
    The European physical journal 33 (2004), S. 261-271 
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    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. We show that forward proton tagging may significantly enlarge the potential of studying the Higgs sector at the LHC. We concentrate on Higgs production via central exclusive diffractive processes (CEDP). Particular attention is paid to regions in the MSSM parameter space where the partial width of the Higgs boson decay into two gluons much exceeds the SM case; here the CEDP are found to have special advantages.
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    URL: http://dx.doi.org/10.1140/epjc/s2003-01566-8
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  • 25
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    The making of the Standard Model (2004)
    Springer
    The European physical journal 34 (2004), S. 5-13 
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    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
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    URL: http://dx.doi.org/10.1140/epjc/s2004-01761-1
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    Physics at the LHC (2004)
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    The European physical journal 34 (2004), S. 51-56 
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    Particle detectors and society (2004)
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    The European physical journal 34 (2004), S. 77-83 
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    CERN press release (2004)
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    The European physical journal 34 (2004), S. 1-2 
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    Superspace gauge fixing of topological Yang-Mills theories (2004)
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    The European physical journal 33 (2004), S. 443-456 
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    Notes: Abstract. We revisit the construction of topological Yang-Mills theories of the Witten type with arbitrary space-time dimension and number of “shift supersymmetry” generators, using a superspace formalism. The super-BF structure of these theories is exploited in order to determine their actions uniquely, up to the ambiguities due to the fixing of the Yang-Mills and BF gauge invariance. UV finiteness to all orders of perturbation theory is proved in a gauge of the Landau type.
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    A precise measurement of the B + , B0 and mean b-hadron lifetime with the DELPHI detector at LEP I (2004)
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    The European physical journal 33 (2004), S. 307-324 
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    Notes: Abstract. Final results from the DELPHI Collaboration on the lifetime of B + and B0 mesons and the mean b-hadron lifetime, are presented using the data collected at the Z 0 peak in 1994 and 1995. Elaborate, inclusive, secondary vertexing methods have been employed to ensure a b-hadron reconstruction with good efficiency. To separate samples of B + and B0 mesons, high performance neural network techniques are used that achieve very high purity signals. The results obtained are: $$ \tau_{\mathrm B}^ + = 1.624 \pm 0.014\;\;(stat) \pm 0.018\; (syst) ps $$ $$ \tau_{\mathrm B}^0\quad = 1.531 \pm 0.021 \;\;(stat)\pm 0.031 \; (syst) ps $$ $$ \frac{\tau_{{\mathrm B}^ + }}{\tau_{{\mathrm B}^0}} = 1.060 \pm 0.021 \;\;(stat)\pm 0.024\;(syst) $$ and for the average b-hadron lifetime: $$ \tau_{{\mathrm b}} = 1.570 \pm 0.005\;\;(stat) \pm 0.008 \; (syst) ps. $$
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    Measurement of charged current triple gauge boson couplings using W pairs at LEP (2004)
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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 pion nucleon coupling constant (2004)
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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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    Perturbation theory for the two-dimensional abelian Higgs modelin the unitary gauge (2004)
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    The European physical journal 32 (2004), S. 261-268 
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    Notes: Abstract. In the unitary gauge the unphysical degrees of freedom of spontaneously broken gauge theories are eliminated. The Feynman rules are simpler than in other gauges, but it is non-renormalizable by the rules of power counting. On the other hand, it is formally equal to the limit $\xi \to 0$ of the renormalizable R $_{\xi}$ -gauge. We consider perturbation theory to one-loop order in the R $_{\xi}$ -gauge and in the unitary gauge for the case of the two-dimensional abelian Higgs model. An apparent conflict between the unitary gauge and the limit $\xi \to 0$ of the R $_{\xi}$ -gauge is resolved, and it is demonstrated that results for physical quantities can be obtained in the unitary gauge.
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    Searching for evolutions from pure states into mixed states with entangled neutral kaons (2004)
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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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    b-tagging in DELPHI at LEP (2004)
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    The European physical journal 32 (2004), S. 299-301 
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    On the multi trace superpotential and corresponding matrix model (2004)
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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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    Power correctionsto the space-like transition form factor ${{F_{\eta^{\prime}g^{*}g^{*}}(Q^2,\omega )}}$ (2004)
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    The European physical journal 32 (2004), S. 507-528 
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    Notes: Abstract. Employing the standard hard-scattering approach (HSA) in conjunction with the running coupling (RC) method, the latter joined with the infrared renormalon calculus, we compute power-suppressed corrections $\sim 1/Q^{2n}, n = 1,2,\ldots $ to the massless $\eta^{\prime}$ -meson-virtual-gluon transition form factor (FF) $Q^2F_{\eta^{\prime}g^{*}g^{*}}(Q^2,\omega)$ . Contributions to the form factor from the quark and gluon components of the $\eta^{\prime}$ meson are taken into account. Analytic expressions for the FFs $F_{\eta^{\prime}gg^{*}}(Q^2,\omega = \pm 1)$ and $F_{\eta^{\prime}g^{*}g^{*}}(Q^2,\omega = 0)$ are also presented, as well as Borel transforms $B[Q^{2}F_{\eta^{\prime}g^{*}g^{*}}](u)$ and resummed expressions. It is shown that except for $\omega = \pm 1,\: 0$ , the Borel transform contains an infinite number of infrared renormalon poles. It is demonstrated that in the explored range of the total gluon virtuality $1 {\mathrm {GeV}}^{2} \leq Q^2 \leq 25 {\mathrm {GeV}}^{2}$ , power corrections found with the RC method considerably enhance the FF $F_{\eta^{\prime}g^{*}g^{*}}(Q^{2}, \omega)$ relative to results obtained only in the context of the standard HSA with a “frozen” coupling.
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    Predictions for $J/\psi$ suppression by parton percolation (2004)
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    The European physical journal 32 (2004), S. 547-553 
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    Notes: Abstract. Parton percolation provides geometric deconfinement in the pre-equilibrium stage of nuclear collisions. The resulting parton condensate can lead to charmonium suppression. We formulate a local percolation condition viable for non-uniform collision environments and show that it correctly reproduces the suppression observed for S-U and Pb-Pb collisions at the SPS. Using this formulation, we then determine the behavior of $J/\psi$ suppression for In-In collisions at the SPS and for Au-Au collisions at RHIC.
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    Affine Toda field theory from tree unitarity (2004)
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    The European physical journal 33 (2004), S. 137-148 
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    Notes: Abstract. The elasticity property (i.e. no particle creation) is used in the tree level scattering of scalar particles in 1 + 1 dimensions to construct affine Toda field theory (ATFT) associated with the root systems of the groups a 2 (2) and c 2 (1). A general prescription is given for constructing ATFT (associated with rank two root systems) with two self-conjugate scalar fields. It is conjectured that the same method could be used to obtain the other ATFT associated with higher rank root systems.
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    DVCS on nuclei: observability and consequences (2004)
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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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    On the generation of Abelian magnetic fieldsin SU(3) gluodynamics at high temperature (2004)
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    The European physical journal 33 (2004), S. 105-112 
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    Notes: Abstract. The vacuum state of SU(3) gluodynamics at high temperature is investigated. A consistent approach including the calculation of the spontaneously generated constant chromomagnetic isotopic H 3 and hypercharge H 8 fields and the polarization operator of charged gluons in this background is applied. It is shown within the effective potential, taking into consideration the one-loop plus daisy diagrams, that the specific values of the fields yield a global minimum to the free energy. The spectrum of the transversal charged modes is stable at high temperature due to the calculated gluon magnetic mass which accounts for the fields. This leads to stable chromomagnetic fields in the deconfinement phase of QCD. A comparison with results of other approaches is made.
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    Tests of the standard model and constraints on new physics from measurements of fermion-pair production at 189-209 GeV at LEP (2004)
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    The European physical journal 33 (2004), S. 173-212 
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    Notes: Abstract. Cross-sections and angular distributions for hadronic and lepton-pair final states in e + e- collisions at centre-of-mass energies between 189 GeV and 209 GeV, measured with the OPAL detector at LEP, are presented and compared with the predictions of the Standard Model. The measurements are used to determine the electromagnetic coupling constant $\alpha_{\mathrm{em}}$ at LEP 2 energies. In addition, the results are used together with OPAL measurements at 91-183 GeV within the S-matrix formalism to determine the $\gamma$ -Z interference term and to make an almost model-independent measurement of the Z mass. Limits on extensions to the Standard Model described by effective four-fermion contact interactions or the addition of a heavy Z’ boson are also presented.
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    Leptoproduction of $\varrho$ mesons within Regge approach (2004)
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    The European physical journal 33 (2004), S. 397-408 
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    Notes: Abstract. A model describing the leptoproduction of $\varrho$ mesons is considered. For the amplitude of the photon dissociation into a $q\bar{q}$ pair, the light-cone wave function is used. Scattering of the colorless $q\bar{q}$ pair off the nucleon is computed within reggeon exchange phenomenology. The transition of the scattered quark and antiquark into the final $\varrho$ meson is treated with the aid of the parton-hadron duality concept. Numerical calculations of $R = \sigma_{\mathrm{L}}/\sigma_{\mathrm{T}}$ and r 04 00 describe the world data at Q 2 〈 4 GeV2 rather reasonably. The calculations of the $\varrho$ meson spin density matrix show that the computed matrix elements except r 04 00 are in good agreement with the available experimental data at Q 2 up to 8 GeV2 and the total mass of the $\gamma p$ system greater than 4 GeV. The Regge phenomenology predictions at the highest experimentally available energies agree with both the HERA data and calculations performed within the perturbative QCD approach even for very high Q 2 ( $\sim 10 $ -20 GeV2). The predicted scale of the S-channel helicity non-conservation is in reasonable agreement with the experimental data.
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    Isospin breaking in $K \rightarrow \pi\pi$ decays (2004)
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    The European physical journal 33 (2004), S. 369-396 
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    Notes: Abstract. We perform a complete analysis of isospin breaking in $K \to 2 \pi$ amplitudes in chiral perturbation theory, including both strong isospin violation ( $m_u \neq m_d$ ) and electromagnetic corrections to next-to-leading order in the low-energy expansion. The unknown chiral couplings are estimated at leading order in the 1/N c expansion. We study the impact of isospin breaking on CP conserving amplitudes and rescattering phases. In particular, we extract the effective couplings g 8 and g 27 from a fit to $K \rightarrow \pi\pi$ branching ratios, finding small deviations from the isospin-limit case. The ratio ${\rm Re} A_0 /{\rm Re} A_2$ measuring the $ \Delta I = 1/2$ enhancement is found to decrease from $22.2 \pm 0.1$ in the isospin limit to $20.3 \pm 0.5$ in the presence of isospin breaking. We also analyze the effect of isospin violation on the CP violation parameter $\epsilon^\prime$ , finding a destructive interference between three different sources of isospin violation. Within the uncertainties of large-N c estimates for the low-energy constants, the isospin violating correction for $\epsilon^\prime$ is below 15%.
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    The radiative return at $\boldsymbol{\Phi}$ - and B-factories: FSR at next-to-leading order (2004)
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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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    Searching for dominant rescattering sources in decays of B to two pseudoscalars (2004)
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    The European physical journal 33 (2004), S. 523-536 
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    Notes: Abstract. Various rescattering sources are analyzed in the context of the SU(3) flavor symmetry. In particular, the possibility to account for intermediate charm at the hadronic level in B to PP is thoroughly investigated. Then, the rescattering sources are compared in light of recent decay measurements of B to two charmless pseudoscalars, with emphasis on the size of strong phases and on patterns of direct CP-asymmetries.
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    The constant background bag model of the hadron (2004)
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    The European physical journal 33 (2004), S. 537-542 
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    Notes: Abstract. We have constructed the bag model having a central constant color field. The motion of the quark is studied in this bag and the Dirac equation is solved for it. The energy spectrum found has a branching due to the interaction of the quarks with the color background. It is pointed out that this model can be applied for taking into account, in the mass spectrum of the hadrons, the coupling of the constituent quarks with the gluon condensation as the interaction with the color background.
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    EPJ C direct (2004)
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    The European physical journal 33 (2004), S. 561-590 
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    Triple gauge vertices at one-loop level in two-Higgs-doublet model (2004)
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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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    Entropy for SU(3) c quark states (2004)
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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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    On Dirac sheet configurations of SU(2) lattice fields (2004)
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    The European physical journal 34 (2004), S. 439-445 
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    Notes: Abstract. Finite temperature Euclidean SU(2) lattice gauge fields close to the deconfinement phase transition are subjected to cooling. We find relatively stable or absolutely stable configurations with an action below the one-instanton action $S_{\mathrm {{inst}}} = 2\pi^2$ both in the deconfinement and the confinement phases. In this paper we attempt to interpret these lowest action configurations. Their action is purely magnetic and amounts to $S/S_{\mathrm {{inst}}} \approx N_{\mathrm {t}}/N_{\mathrm {s}}$ , where N t (N s) is the timelike (spacelike) lattice size, while the topological charge vanishes. In the confined phase part of the corresponding lattice configurations turns out to be absolutely stable with respect to the cooling process in which case Abelian projection reveals a homogeneous, purely Abelian magnetic field closed over the “boundary” in one of the spatial directions. Referring to the dyonic structure established for the confinement phase near T c and based on the observation made for this phase that such events below the instanton action S inst emerge from dyon-antidyon annihilation, the question of the stability (metastability) is discussed for both phases. The hypothetically different dyonic structure of the deconfinement phase, inaccessible by cooling, could explain the metastability.
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    K e3 decays and CKM unitarity (2004)
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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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    Isolated photon plus jet photoproduction as a toolto constrain the gluon distribution in the proton and the photon (2004)
    Springer
    The European physical journal 34 (2004), S. 191-199 
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    Notes: Abstract. We analyse how the reaction $\gamma p \to \gamma + {\mathrm{jet}} + X$ can serve to constrain the gluon distributions. Our results are based on a code of partonic event generator type which includes full NLO corrections. We conclude that there are phase space domains in which either the gluon in the photon or the gluon in the proton give important contributions to the cross section, which should be observable in HERA experiments.
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    Reduction method for dimensionally regulatedone-loop N-point Feynman integrals (2004)
    Springer
    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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    Finite supersymmetry transformations (2004)
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    The European physical journal 35 (2004), S. 119-127 
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    Notes: Abstract. We investigate simple examples of supersymmetry algebras with real and Grassmann parameters. Special attention is paid to the finite supertransformations and their probability interpretation. Furthermore we look for combinations of bosons and fermions which are invariant under supertransformations. These combinations correspond to states that are highly entangled.
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    Testing non-commutative QED $\gamma\gamma\gamma$ and $\gamma\gamma\gamma\gamma$ couplings at LHC (2004)
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    The European physical journal 35 (2004), S. 137-143 
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    Notes: Abstract. In this work, we investigate the sensitivity of the process $p + p \to q + q \to j + j + \gamma + \gamma $ at LHC for the photonic 3- and 4-point functions that appear in non-commutative QED. We show that this process serves to study the behavior of the space-space as well as of the space-time non-commutativity. We also show that this process can probe the non-commutative scale $\Lambda$ in the range of a few TeV.
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    Solution of twist-3 evolution equation in double logarithmic approximation in QCD (2004)
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    The European physical journal 35 (2004), S. 99-104 
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    Notes: Abstract. The solution of the DGLAP evolution equation for the twist-3 gluon operators is obtained in the double logarithmic approximation of QCD perturbation theory. The method used for the solution is similar to the reggeon field theory. The asymptotics of the twist-3 parton correlation function for small Bjorken variables x B is found.
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    Spectrum and decays of kaonic hydrogen (2004)
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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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    $SU(3)_c\otimes SU(4)_{\mathrm {L}}\otimes U(1)_X$ model for three families (2004)
    Springer
    The European physical journal 35 (2004), S. 259-265 
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    Notes: Abstract. An extension of the standard model to the local gauge group $SU(3)_c\otimes SU(4)_{\mathrm {L}}\otimes U(1)_X$ as a three-family model is presented. The model does not contain exotic electric charges and we obtain a consistent mass spectrum by introducing an anomaly-free discrete Z 2 symmetry. The neutral currents coupled to all neutral vector bosons in the model are studied. By using experimental results from the CERN LEP, SLAC Linear Collider and atomic parity violation data we constrain the mixing angle between two of the neutral currents in the model and the mass of the additional neutral gauge bosons to be $-0.0032\leq\sin\theta\leq 0.0031$ and $0.67 \hbox{TeV}\leq M_{Z_2} \leq 6.1$ TeV at $95 \%$ C.L., respectively.
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    Transversity distribution function in hard scatteringof polarized protons and antiprotons in the PAX experiment (2004)
    Springer
    The European physical journal 35 (2004), S. 207-210 
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    Notes: Abstract. Estimates are given for the double spin asymmetry in lepton-pair production from collisions of transversely polarized protons and antiprotons for the kinematics of the recently proposed PAX experiment at GSI on the basis of predictions for the transversity distribution from the chiral quark soliton model.
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    Energy dependence of Cronin momentum in saturation model for p + A and A + A collisions (2004)
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    The European physical journal 35 (2004), S. 359-364 
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    Notes: Abstract. The energy dependence of the Cronin momentum for p + A and A + A collisions in the saturation model are calculated. This dependence is consistent with simple dimensional considerations and can be used to test the validity of the saturation model. It gives the possibility to distinguish the different variants of the saturation model with precise experimental data and to measure the x dependence of the saturation momentum.
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    Determining resonance parameters of heavy Higgs bosonsat a future linear collider (2004)
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    The European physical journal 35 (2004), S. 171-176 
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    Notes: Abstract. This study investigates the potential of an Electron-Positron Linear Collider for measuring resonance parameters of Higgs bosons beyond the mass range studied so far. The analysis is based on the reconstruction of events from the Higgs-strahlung process $\mathrm{e}^ + \mathrm{e}^-\to\mathrm{HZ}$ . It is shown that the total width $\Gamma_{tot}^{\mathrm{H}}$ , the mass m H and the event rate N can be measured from the mass spectrum in a model independent way. Also, the branching ratios BR H WW and BR H ZZ can be measured, assuming these are the only relevant Higgs decay modes. The simulation includes realistic detector effects and all relevant Standard Model background processes. Results are given for m H = 200-320 GeV assuming ${\cal \int\!\! L} = 500$ fb-1 integrated luminosity at a collision energy $\sqrt{s} = 500$ GeV.
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    Tests of models of color reconnection and a search for glueballs using gluon jets with a rapidity gap (2004)
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    The European physical journal 35 (2004), S. 293-312 
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    Notes: Abstract. Gluon jets with a mean energy of 22 GeV and purity of 95% are selected from hadronic Z0 decay events produced in e + e- annihilations. A subsample of these jets is identified which exhibits a large gap in the rapidity distribution of particles within the jet. After imposing the requirement of a rapidity gap, the gluon jet purity is 86%. These jets are observed to demonstrate a high degree of sensitivity to the presence of color reconnection, i.e. higher order QCD processes affecting the underlying color structure. We use our data to test three QCD models which include a simulation of color reconnection: one in the Ariadne Monte Carlo, one in the Herwig Monte Carlo, and the other by Rathsman in the Pythia Monte Carlo. We find the Rathsman and Ariadne color reconnection models can describe our gluon jet measurements only if very large values are used for the cutoff parameters which serve to terminate the parton showers, and that the description of inclusive Z0 data is significantly degraded in this case. We conclude that color reconnection as implemented by these two models is disfavored. The signal from the Herwig color reconnection model is less clear and we do not obtain a definite conclusion concerning this model. In a separate study, we follow recent theoretical suggestions and search for glueball-like objects in the leading part of the gluon jets. No clear evidence is observed for these objects.
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    Quasi-degenerate neutrinos and lepton flavor violationin supersymmetric models (2004)
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    The European physical journal 35 (2004), S. 365-372 
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    Notes: Abstract. In supersymmetric models the misalignment between fermion and sfermion families introduces unsuppressed flavor-changing processes. Even if the mass parameters are chosen to give no flavor violation, family dependent radiative corrections make this adjustment not stable. We analyze the rate of $\ell\rightarrow\ell'\gamma$ in SUSY-GUT models with three quasi-degenerate neutrinos and universal scalar masses at the Planck scale. We pay special attention to a recently proposed scenario where the low-energy neutrino mixings are generated from identical quark and lepton mixings at large scales. We show the following. (i) To take universal slepton masses at the GUT scale is a very poor approximation, even in no-scale models. (ii) For large neutrino Yukawa couplings the decay $\mu\rightarrow e\gamma$ would be observed in the planned experiment at PSI. (iii) For large values of $\tan\beta$ the tau coupling gives important corrections, pushing $\mu\rightarrow e\gamma$ and $\tau\rightarrow \mu\gamma$ to accessible rates. In particular, the non-observation of these processes in the near future would exclude the scenario with unification of quark and lepton mixing angles. (iv) The absence of lepton flavor violating decays in upcoming experiments would imply a low value of $\tan\beta$ , small neutrino couplings, and large ( $\gtrsim 250$ GeV) SUSY-breaking masses.
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    The $\beta$ -function in duality-covariant non-commutative $\phi^4$ -theory (2004)
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    The European physical journal 35 (2004), S. 277-282 
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    Notes: Abstract. We compute the one-loop $\beta$ -functions describing the renormalisation of the coupling constant $\lambda$ and the frequency parameter $\Omega$ for the real four-dimensional duality-covariant non-commutative $\phi^4$ -model, which is renormalisable to all orders. The contribution from the one-loop four-point function is reduced by the one-loop wavefunction renormalisation, but the $\beta_\lambda$ -function remains non-negative. Both $\beta_\lambda$ and $\beta_\Omega$ vanish at the one-loop level for the duality-invariant model characterised by $\Omega = 1$ . Moreover, $\beta_\Omega$ also vanishes in the limit $\Omega\to 0$ , which defines the standard non-commutative $\phi^4$ -quantum field theory. Thus, the limit $\Omega\to 0$ exists at least at the one-loop level.
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    Angular symmetry breaking induced by electromagnetic field (2004)
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    The European physical journal 35 (2004), S. 373-381 
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    Notes: Abstract. It is well known that velocities do not commute in the presence of an electromagnetic field. This property implies that angular algebra symmetries, such as the sO(3) and Lorentz algebra symmetries, are broken. To restore these angular symmetries we show the necessity of adding the Poincaré momentum M to the simple angular momentum L. These restorations performed successively in a flat space and in a curved space lead in each case to the generation of a Dirac magnetic monopole. In the particular case of the Lorentz algebra we consider an application of our theory to gravitoelectromagnetism. In this last case we establish a qualitative relation giving the mass spectrum for dyons.
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    Search for fermiophobic Higgs bosons in final states with photons at LEP 2 (2004)
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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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    Complete description of polarization effects in emission of a photon by an electron in the field of a strong laser wave (2004)
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    The European physical journal 36 (2004), S. 127-145 
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    Notes: Abstract. We consider the emission of a photon by an electron in the field of a strong laser wave. Polarization effects in this process are important for a number of physical problems. The probability of this process for circularly or linearly polarized laser photons and for arbitrary polarization of all other particles is calculated. We obtain the complete set of functions which describe such a probability in a compact invariant form. Besides this, we discuss in some detail the polarization effects in the kinematics relevant to the problem of $e\to \gamma$ conversion at $\gamma \gamma$ and $\gamma e$ colliders.
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    On the classical dynamics of charges in non-commutative QED (2004)
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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 evolution of hadron spectra in the modified leading logarithm approximation (2004)
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    The European physical journal 36 (2004), S. 49-56 
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    Notes: Abstract. We perform fits of $\Lambda_{\mathrm {QCD}}$ and the gluon fragmentation function D(x,Q) at initial scale $Q_0 \gg\Lambda_{\mathrm {QCD}}$ to charged light hadron momentum spectra data by evolving in the modified leading logarithm approximation. Without additional assumptions, we achieve a good description of the available data for $\xi = \ln(1/x)$ up to and around the Gaussian peak, and values of $\Lambda_{\mathrm {QCD}}$ acceptably close to those in the literature. In particular, we find that this procedure describes the position of the peak, and, in contrast to the limiting spectrum, also the normalization.
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    Diffractive large transferred momentum photoproduction of vector mesons (2004)
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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 rare $\bar{B}^0_{d} \to \phi\gamma$ decays in the standard model and as a probe of R-parity violation (2004)
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    The European physical journal 36 (2004), S. 97-102 
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    Notes: Abstract. We present a first study of the rare annihilation decay $\bar{B}^0_d \to \phi\gamma$ in the standard model. Using the QCD factorization formalism, we find ${\cal B}(\bar{B}^0_d \to\phi\gamma ) = 3.6\times 10^{-12}$ . The smallness of the decay rate in the standard model makes the decay a sensitive probe of new physics contributions. As an example, we calculate the effects of R-parity violating couplings. Within the available upper bounds for $\smash{\vert\lambda^{"}_{i23}\lambda^{"*}_{i12}\vert}$ and $\smash{\vert\lambda^{'}_{i32}\lambda^{'*}_{i12}\vert}$ , $\smash{{\cal B}(\bar{B}^0_d \to\phi\gamma )}$ could be enhanced to the order of $10^{-9}\sim 10^{-8}$ , which might be accessible at LHCB, B-TeV and the planned super high luminosity B factories at KEK and SLAC.
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    The rare decay $K_{\mathrm{L}} \rightarrow\pi^{0} \mu^{ + } \mu^{-}$ within the SM (2004)
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    The European physical journal 36 (2004), S. 57-66 
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    Notes: Abstract. We present an updated analysis of the rare decay $K_{\mathrm{L}} \rightarrow\pi^{0} \mu^{ + } \mu^{-}$ within the standard model. In particular, we present the first complete calculation of the two-photon CP-conserving amplitude within chiral perturbation theory, at the lowest non-trivial order. Our results confirm the previous findings that the CP-conserving contribution to the decay rate cannot be neglected. By means of an explicit two-loop calculation, we show that this contribution can be estimated with sufficient accuracy compared to the CP-violating terms. We predict ${\cal B}(K_{\mathrm{L}}\rightarrow\pi^{0}\mu^{ + } \mu^{-})_{\mathrm{SM}} = (1.5\pm0.3)\times10^{-11}$ , with approximately equal contributions from the CP-conserving component, the indirect-CP-violating term, and the interesting direct-CP-violating amplitude. The error of this prediction is mainly of parametric nature and could be substantially reduced with better data on the $K_{\mathrm{S}}\rightarrow\pi^{0}\ell^{ + }\ell^{-}$ modes. The standard model predictions for various differential distributions and the sensitivity to possible new-physics effects are also briefly discussed.
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    On the direct CP-violation parameter $\epsilon'$ (2004)
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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 photon-neutrino interaction induced by non-commutativity and astrophysical bounds (2004)
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    The European physical journal 36 (2004), S. 405-410 
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    Notes: Abstract. In this work we propose a possible mechanism of left- and right-handed neutrino couplings to photons, which arises quite naturally in non-commutative field theory. We estimate the predicted additional energy-loss in stars induced by space-time non-commutativity. The usual requirement that any new energy-loss mechanism in globular stellar clusters should not excessively exceed the standard neutrino losses implies a scale of non-commutative gauge theory above the scale of weak interactions.
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    Alternative approach to $B^- \to \eta^{\prime} K^-$ branching ratio calculation (2004)
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    The European physical journal 36 (2004), S. 215-220 
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    Notes: Abstract. Since the calculation of ${\mathrm {BR}}(B^- \to \eta^{\prime} K^-)$ in the framework of the QCD improved factorization method developed by Beneke et al. leads to numerical values much below the experimental data, we include two different contributions, in an alternative way. First, we find that the spectator hard-scattering mechanism increases the BR value with almost $50 \%$ , but the predictions depend on the combined singularities in the amplitude convolution. Secondly, by adding SUSY contributions to the Wilson coefficients, we come to a BR depending on three parameters, whose values are constrained by the experimental data.
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    Gauge fixing of Chern-Simons N-extended supergravity (2004)
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    The European physical journal 36 (2004), S. 245-249 
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    Notes: Abstract. We treat N-extended supergravity in 2 + 1 space-time dimensions as a Yang-Mills gauge field with Chern-Simons action associated to the N-extended Poincaré supergroup. We fix the gauge of this theory within the Batalin-Vilkovisky scheme.
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    An analysis of the time-dependent CP asymmetryin $B \to \pi \pi$ decays in the standard model (2004)
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    The European physical journal 36 (2004), S. 183-200 
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    Notes: Abstract. Measurements of the time-dependent CP-asymmetry in the decay $B^0_d (t)\to \pi^ + \pi^-$ and its charge conjugate by the BELLE and BABAR collaborations currently yield $C_{\pi \pi}^{ + -} = -0.46 \pm 0.13$ and $S_{\pi \pi}^{ + -} = -0.74 \pm 0.16$ , characterizing the direct and mixing-induced CP-asymmetries, respectively. We study the implication of these measurements on the CKM phenomenology taking into account the available information in the quark mixing sector. Our analysis leads to the results that the ratio |P c /T c | involving the QCD-penguin and tree amplitudes and the related strong phase difference $\delta_c = \delta_c^P - \delta_c^T$ in the $B^0_d/\bar{B}_d^0 \to \pi^ + \pi^-$ decays are quite substantial. Using the isospin symmetry to constrain |P c /T c | and $\cos (2\theta)$ , where $2 \theta$ parameterizes the penguin-induced contribution, we present a fit of the current data including the measurements of $S_{\pi \pi}^{ + -}$ and $C_{\pi \pi}^{ + -}$ . Our best-fits yield $\alpha = 92^\circ$ , $\beta = 24^\circ$ , $\gamma = 64^\circ$ , $\vert P_c/T_{\mathrm c}\vert = 0.77$ , and $\delta_c = -43^\circ$ . At 68% C.L., the ranges are $81^\circ \leq \alpha \leq 103^\circ$ , $21.9^\circ \leq \beta \leq 25.5^\circ$ , $54^\circ \leq \gamma \leq 75^\circ$ , $0.43 \leq \vert P_c/T_{\mathrm c}\vert \leq 1.35$ and $-64^\circ \leq \delta_c \leq -29^\circ$ . Currently en vogue dynamical approaches to estimate the hadronic matrix elements in $B \to \pi \pi$ decays do not provide a good fit of the current data.
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    URL: http://dx.doi.org/10.1140/epjc/s2004-01883-4
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    Threshold corrections in bottom and charm quark hadroproduction at next-to-next-to-leading order (2004)
    Springer
    The European physical journal 36 (2004), S. 201-213 
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    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    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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    URL: http://dx.doi.org/10.1140/epjc/s2004-01894-1
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    Symmetry realization of texture zeros (2004)
    Springer
    The European physical journal 36 (2004), S. 227-232 
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    ISSN: 1434-6052
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    Topics: Physics
    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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    A modified cluster-hadronisation model (2004)
    Springer
    The European physical journal 36 (2004), S. 381-395 
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    ISSN: 1434-6052
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    Topics: Physics
    Notes: Abstract. A new phenomenological cluster-hadronisation model is presented. Its specific features are the incorporation of soft colour reconnection, a more general treatment of diquarks including their spin and giving rise to clusters with baryonic quantum numbers, and a dynamic separation of the regimes of clusters and hadrons according to their masses and flavours. The distinction between the two regions automatically leads to different cluster decay and transformation modes. Additionally, these aspects require an extension of individual cluster-decay channels that were available in previous versions of such models.
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    URL: http://dx.doi.org/10.1140/epjc/s2004-01960-8
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    Spectra and decays of $\pi \pi$ and $\pi K$ atoms (2004)
    Springer
    The European physical journal 36 (2004), S. 483-501 
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    ISSN: 1434-6052
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    Topics: Physics
    Notes: Abstract. We describe the spectra and decays of $\pi^ + \pi^-$ and $\pi^\pm K^\mp$ atoms within a non-relativistic effective field theory. The evaluations of the energy shifts and widths are performed at next-to-leading order in isospin symmetry breaking. We provide general formulae for all S-states, and discuss the states with angular momentum one in some detail. The prediction for the lifetime of the $\pi^\pm K^\mp$ atom in its ground state yields $\tau_{10} = (3.7\pm0.4)\cdot10^{-15}$ s.
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    $B \rightarrow \eta_c K(\eta_c^\prime K)$ decays in QCD factorization (2004)
    Springer
    The European physical journal 36 (2004), S. 365-370 
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    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    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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    URL: http://dx.doi.org/10.1140/epjc/s2004-01945-7
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    W & Z physics at LEP (2004)
    Springer
    The European physical journal 36 (2004), S. 411-411 
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    ISSN: 1434-6052
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    Topics: Physics
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    URL: http://dx.doi.org/10.1140/epjc/s2004-01975-1
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    Genuine twist-3 contributions to the generalized parton distributionsfrom instantons (2004)
    Springer
    The European physical journal 37 (2004), S. 105-114 
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    ISSN: 1434-6052
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    Topics: Physics
    Notes: Abstract. The genuine twist-3 quark-gluon ( $\bar{q} G q$ ) contributions to the generalized parton distributions (GPDs) are estimated in the model of the instanton vacuum. These twist-3 effects are found to be parametrically suppressed relative to the “kinematical” twist-3 ones due to the small packing fraction of the instanton vacuum. We derived exact sum rules for the twist-3 GPDs.
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    Neutrino dipole moments and charge radii in non-commutative space-time (2004)
    Springer
    The European physical journal 37 (2004), S. 123-128 
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    ISSN: 1434-6052
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    Topics: Physics
    Notes: Abstract. In this paper we obtain a bound $\Lambda_{\mathrm {NC}}\stackrel{ 〈 }{\sim} 150 $ TeV on the scale of space-time non-commutativity considering photon-neutrino interactions. We compute “*-dipole moments” and “*-charge radii” originating from space-time non-commutativity and compare them with the dipole moments calculated in the neutrino-mass extended standard model (SM). The computation depends on the nature of the neutrinos, Dirac versus Majorana, their mass and the energy scale. We focus on Majorana neutrinos. The “*-charge radius” is found to be $r^* = \sqrt{|\langle r^2_{\nu}\rangle_{\mathrm {NC}}|}=\left|3\sum_{i=1}^3 ({\theta}^{0i})^2\right|^{1/4} \stackrel{〈}{\sim} 1.6 \times 10^{-19}\, {\mathrm {cm}}$ at $\Lambda_{\mathrm {NC}} = 150$ TeV.
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    URL: http://dx.doi.org/10.1140/epjc/s2004-01969-y
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    Search for supersymmetric particles assuming R-parity non-conservation in e + e- collisions at $\sqrt{s} = 192$ to 208 GeV (2004)
    Springer
    The European physical journal 37 (2004), S. 129-131 
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    ISSN: 1434-6052
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    Topics: Physics
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    URL: http://dx.doi.org/10.1140/epjc/s2004-01976-0
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    $J/\psi$ gluonic dissociation revisited: I. Fugacity, flux and formation time effects (2004)
    Springer
    The European physical journal 37 (2004), S. 115-121 
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    ISSN: 1434-6052
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    Topics: Physics
    Notes: Abstract. We revisit the standard treatment due to Xu et al. of $J/\psi$ suppression due to gluonic bombardment in an equilibrating quark-gluon plasma. Effects arising from gluon fugacity, relative g- $\psi$ flux, and $\psi$ meson formation time are explicitly incorporated in the formulation of the gluon number density, velocity-weighted cross section, and the survival probability. Our new formulae are applied to a numerical study of the pattern of $J/\psi$ suppression in the central rapidity region at RHIC/LHC energies. The temperature and transverse momentum dependence of our graphs have noticeable differences from those of Xu et al.
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    Stochastic analysis of different rough surfaces (2004)
    Springer
    The European physical journal 41 (2004), S. 259-277 
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    ISSN: 1434-6036
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    Topics: Physics
    Notes: Abstract. This paper shows in detail the application of a new stochastic approach for the characterization of surface height profiles, which is based on the theory of Markov processes. With this analysis we achieve a characterization of the scale dependent complexity of surface roughness by means of a Fokker-Planck or Langevin equation, providing the complete stochastic information of multiscale joint probabilities. The method is applied to several surfaces with different properties, for the purpose of showing the utility of this method in more detail. In particular we show evidence of the Markov properties, and we estimate the parameters of the Fokker-Planck equation by pure, parameter-free data analysis. The resulting Fokker-Planck equations are verified by numerical reconstruction of the conditional probability density functions. The results are compared with those from the analysis of multi-affine and extended multi-affine scaling properties which is often used for surface topographies. The different surface structures analysed here show in detail the advantages and disadvantages of these methods.
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    URL: http://dx.doi.org/10.1140/epjb/e2004-00317-4
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    Specific heat of magnetic Ce alloys within a two-component model (2004)
    Springer
    The European physical journal 41 (2004), S. 289-294 
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    ISSN: 1434-6036
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    Topics: Physics
    Notes: Abstract. We propose a description of the electronic properties of Ce alloys as an inhomogeneous mixture of two components: one containing magnetic Ce ions with an RKKY interaction J H between them, and the other described as a collection of Kondo impurities with exchange interaction J K . Both J H and J K are assumed to depend on a composition parameter X, with a Gaussian distribution around a value X 0 (near to the expectation value of X), related to the experimental composition parameter x of the alloy. When the concentration of the Kondo impurities is large, the specific heat C displays non-Fermi liquid behavior over a wide temperature range. The main qualitative features of C/T as a function of temperature T observed in several Ce alloys are reproduced using simple J H (X) and J K (X) dependences.
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    URL: http://dx.doi.org/10.1140/epjb/e2004-00319-2
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    Influence of the Coulomb parameter U on partial densities of states of CuGeO $_\mathsf{3}$ : comparison with X-ray spectral data (2004)
    Springer
    The European physical journal 41 (2004), S. 295-300 
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    ISSN: 1434-6036
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    Topics: Physics
    Notes: Abstract. The electronic structure of the strongly Coulomb correlated cuprate CuGeO3 has been calculated by the local-density-approximation method (LDA + U). The parameter U was varied from 0 to 8 eV. The results of the band-structure calculations are compared with experimental data obtained by means of X-ray photoelectron and resonant X-ray emission spectroscopy methods (Cu L $\alpha$ and O K $\alpha$ X-ray emission spectra). It is established that a LDA + U calculation with U = 4 eV reproduces well the X-ray photoelectron and X-ray resonant emission spectral data.
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    URL: http://dx.doi.org/10.1140/epjb/e2004-00320-9
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    Temperature stable low loss ceramic dielectrics in (1-x)ZnAl $\mathsf{_{2}}$ O $\mathsf{_{4}}$ -xTiO $\mathsf{_{2}}$ system for microwave substrate applications (2004)
    Springer
    The European physical journal 41 (2004), S. 301-306 
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    ISSN: 1434-6036
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    Topics: Physics
    Notes: Abstract. The microwave dielectric properties of ZnAl2O4 spinels were investigated and their properties were tailored by adding different mole fractions of TiO2. The samples were synthesized using the mixed oxide route. The phase purity and crystal structure were identified using X-ray diffraction technique. The sintered specimens were characterized in the microwave frequency range (3-13 GHz). The ZnAl2O4 ceramics exhibited interesting dielectric properties (dielectric constant ( $\varepsilon_{r}) = 8.5$ , unloaded quality factor (Q u ) = 4590 at 12.27 GHz and temperature coefficient of resonant frequency ( $\tau_{f}) = -79$ ppm/ $^{\circ}$ C). Addition of TiO2 into the spinel improved its properties and the $\tau_{f}$ approached zero for 0.83ZnAl2O4-0.17TiO2. This temperature compensated composition has excellent microwave dielectric properties ( $\varepsilon _{r} = 12.67$ , Q u = 9950 at 10.075 GHz) which can be exploited for microwave substrate applications.
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    Microwave properties of Ba $\mathsf{_{0.6}}$ K $\mathsf{_{0.4}}$ BiO $\mathsf{_3}$ crystals (2004)
    Springer
    The European physical journal 41 (2004), S. 313-318 
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    ISSN: 1434-6036
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    Topics: Physics
    Notes: Abstract. We report on field-induced variations of the microwave surface resistance at 9.6 GHz of Ba0.6K0.4BiO3 crystals. Energy losses have been investigated as a function of the static magnetic field in the range of temperatures 4.2 K $\div T_c$ . By analyzing the experimental results in the framework of the Coffey and Clem model we determine the temperature dependence of the first-penetration field, upper critical field and depinning frequency. The results show that the pinning energy of this bismuthate superconductor is weaker than those of cuprates.
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    Roles of interfaces in nanostructured silicon luminescence (2004)
    Springer
    The European physical journal 41 (2004), S. 325-332 
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    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. The increasing interest in photonics in the field of communication has led to intense research work on silicon based nanostructures showing efficient photoluminescence. The present paper reports photoluminescence measurements obtained at room temperature in silicon-rich-silica-silica multilayers grown by reactive magnetron sputtering. The silicon nanograin size is controlled via the silicon layer thickness which can be monitored with high accuracy. We aim to develop a comprehensive understanding of the combined roles played by the quantum confinement effect through the silicon grain size and the existence of an interfacial region between the grain and the surrounding silica matrix. Two bands of photoluminescence are displayed in the 600 nm-900 nm range and correspond to the bands previously observed at 2 K. Their origin is demonstrated through a model based on the solution of the Schrödinger equation of the exciton wavefunction in a one-dimension geometry corresponding to the growth direction of the multilayers. The silicon layer as well as the Si-SiO2 interface thicknesses are the key parameters of the photoluminescence features.
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    Evolution of the initially ordered structure in a magnetic fluid film during a thermal cycle (2004)
    Springer
    The European physical journal 41 (2004), S. 319-323 
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    Topics: Physics
    Notes: Abstract. A hexagonal ordered structure of magnetic columns, which results from an agglomeration of magnetic particles, is obtained in a magnetic fluid film when a magnetic field is applied perpendicularly to the film surface. The evolution of the initially ordered structure in the magnetic fluid film during the heating and cooling process is investigated under a given magnetic field. For the heating process, the columns remain unchanged until the temperature exceeds a critical temperature. As the temperature is further increased, column particles start to disperse into the liquid carrier. As a result, portions of columns disappear. As the temperature continue to rise, the ordered structure changes to a disordered column state, or even a monodispersed state. On the other hand, when the temperature is lowered, the magnetic particles in the carrier condense out of solution and finally an ordered structure of columns is achieved. However, this structural evolution during a thermal cycle is irreversible.
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    Dependence of the average to-node distance on the node degree for random graphs and growing networks (2004)
    Springer
    The European physical journal 41 (2004), S. 333-336 
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    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. In a connected graph, nodes can be characterised locally (with their degree k) or globally (e.g. with their average length path $\xi$ to other nodes). Here we investigate how $\xi$ depends on k. The numerical algorithm based on the construction of the distance matrix is applied to random graphs and the growing networks: the scale-free ones and the exponential ones. The results are relevant for search strategies in different networks.
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    Hopf bifurcation and chaos in a single inertial neuron model with time delay (2004)
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    The European physical journal 41 (2004), S. 337-343 
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    Topics: Physics
    Notes: Abstract. A delayed differential equation modelling a single neuron with inertial term subject to time delay is considered in this paper. Hopf bifurcation is studied by using the normal form theory of retarded functional differential equations. When adopting a nonmonotonic activation function, chaotic behavior is observed. Phase plots, waveform plots, and power spectra are presented to confirm the chaoticity.
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    A parsimonious and universal description of turbulent velocity increments (2004)
    Springer
    The European physical journal 41 (2004), S. 345-363 
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    ISSN: 1434-6036
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    Topics: Physics
    Notes: Abstract. This paper proposes a reformulation and extension of the concept of Extended Self-Similarity. In support of this new hypothesis, we discuss an analysis of the probability density function (pdf) of turbulent velocity increments based on the class of normal inverse Gaussian distributions. It allows for a parsimonious description of velocity increments that covers the whole range of amplitudes and all accessible scales from the finest resolution up to the integral scale. The analysis is performed for three different data sets obtained from a wind tunnel experiment, a free-jet experiment and an atmospheric boundary layer experiment with Taylor-Reynolds numbers $R_{\lambda} = 80,190,17000$ , respectively. The application of a time change in terms of the scale parameter $\delta$ of the normal inverse Gaussian distribution reveals some universal features that are inherent to the pdf of all three data sets.
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    Large deviations in spin-glass ground-state energies (2004)
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    The European physical journal 41 (2004), S. 365-375 
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    ISSN: 1434-6036
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    Topics: Physics
    Notes: Abstract. The ground-state energy E 0 of a spin glass is an example of an extreme statistic. We consider the large deviations of this energy for a variety of models when the number of spins N goes to infinity. In most cases, the behavior can be understood qualitatively, in particular with the help of semi-analytical results for hierarchical lattices. Particular attention is paid to the Sherrington-Kirkpatrick model; after comparing to the Tracy-Widom distribution which follows from the spherical approximation, we find that the large deviations give rise to non-trivial scaling laws with N.
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    An extension to the Wheeler phase-field model to allow decoupling of the capillary and kinetic anisotropies (2004)
    Springer
    The European physical journal 41 (2004), S. 377-382 
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    Topics: Physics
    Notes: Abstract. The formulation of the phase-field problem due to Wheeler et al. [Physica D 66, 243 (1993)] has been adopted and extended as a tool for solidification research by many groups around the World. However, an intrinsic problem of this model is that it couples two physically distinct anisotropies, those associated with the surface energy of the solid-liquid interface and attachment kinetics, into a single anisotropy parameter. In this paper we present a simple extension to the Wheeler model in which we show that introducing a complex form of the anisotropy function allows these two physical parameters to be decoupled.
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    URL: http://dx.doi.org/10.1140/epjb/e2004-00330-7
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