Pseudoscalar Form Factors in Tau-Neutrino Nucleon Scattering

We investigate the pseudoscalar transition form factors of nucleon for quasi-elastic scattering and \Delta resonance production in tau-neutrino nucleon scattering via the charged current interactions. Although the pseudoscalar form factors play an important role for the \tau production in neutrino-nucleon scattering, these are not known well. In this article, we examine their effects in quasi-elastic scattering and \Delta resonance production and find that the cross section, Q^{2} distribution, and spin polarization of the produced \tau^{\pm} leptons are quite sensitive to the pseudoscalar form factors.Comment: 7 pages, 3 figure

Bound-state effects in t¯t production at hadron colliders

We discuss the bound-state effects in t¯t production at hadron colliders. The effects can be sizable in the threshold region at the LHC, where t¯t pairs are predominantly produced via gluon-fusion process. The t¯t invariant-mass distribution as well as the top-quarks kinematical distributions are investigated. A prospect for the mass determination using the threshold events is discussed

Tau polarization effects in the CNGS tau-neutrino appearance experiments

We studied tau polarization effects on the decay distributions of tau produced in the CNGS tau-neutrino appearance experiments. We show that energy and angular distributions for the decay products in the laboratory frame are significantly affected by the tau polarization. Rather strong azimuthal asymmetry about the tau momentum axis is predicted, which may have observable consequences in experiments even with small statistics.Comment: 5 pages, 6 eps figures, espcrc2.sty; Proceedings of the 4th International Workshop on Neutrino-Nucleus Interactions in the Few GeV Region (NuInt05), September 26-29, 2005, Okayama, Japa

Photoemission Quasi-Particle Spectra of Sr2_2RuO4_4

Multi-band quasi-particle calculations based on perturbation theory and dynamical mean field methods show that the creation of a photoemission hole state in Sr$_2$RuO$_4$ is associated with a highly anisotropic self-energy. Since the narrow Ru-derived $d_{xz,yz}$ bands are more strongly distorted by Coulomb correlations than the wide $d_{xy}$ band, charge is partially transferred from $d_{xz,yz}$ to $d_{xy}$, thereby shifting the $d_{xy}$ van Hove singularity close to the Fermi level.Comment: 4 pages, to be published in PRB Rapid Com

Coherent Beam-Beam Tune Shift of Unsymmetrical Beam-Beam Interactions with Large Beam-Beam Parameter

Coherent beam-beam tune shift of unsymmetrical beam-beam interactions was studied experimentally and numerically in HERA where the lepton beam has a very large beam-beam parameter (up to $\xi_y=0.272$). Unlike the symmetrical case of beam-beam interactions, the ratio of the coherent and incoherent beam-beam tune shift in this unsymmetrical case of beam-beam interactions was found to decrease monotonically with increase of the beam-beam parameter. The results of self-consistent beam-beam simulation, the linearized Vlasov equation, and the rigid-beam model were compared with the experimental measurement. It was found that the coherent beam-beam tune shifts measured in the experiment and calculated in the simulation agree remarkably well but they are much smaller than those calculated by the linearized Vlasov equation with the single-mode approximation or the rigid-beam model. The study indicated that the single-mode approximation in the linearization of Vlasov equation is not valid in the case of unsymmetrical beam-beam interactions. The rigid-beam model is valid only with a small beam-beam parameter in the case of unsymmetrical beam-beam interactions.Comment: 32 pages, 13 figure

Polarization effects in tau production by neutrino

We studied polarization effects in tau production by neutrino-nucleon scattering. Quasi-elastic scattering, $Delta$ resonance production and deep inelastic scattering processes are taken into account for the CERN-to-Gran Sasso projects. We show that the tau produced by neutrino has high degree of polarization, and its spin direction depends non-trivially on the energy and the scattering angle of tau in the laboratory frame.Comment: 6 pages, 5 eps figures, espcrc2.sty; Proceedings of the 3rd International Workshop on Neutrino-Nucleus Interactions in the Few GeV Region (NuInt04), March 17-21, 2004, Gran Sasso, Italy; minor changes, typos in Eq. (6) correcte

Superconductivity at 5.2 K in ZrTe3 polycrystals and the effect of Cu, Ag intercalation

We report the occurrence of superconductivity in polycrystalline samples of ZrTe3 at 5.2 K temperature at ambient pressure. The superconducting state coexists with the charge density wave (CDW) phase, which sets in at 63K. The intercalation of Cu or Ag, does not have any bearing on the superconducting transition temperature but suppresses the CDW state. The feature of CDW anomaly in these compounds is clearly seen in the DC magnetization data. Resistivity data is analysed to estimate the relative loss of carriers and reduction in the nested Fermi surface area upon CDW formation in the ZrTe3 and the intercalated compounds.Comment: 5 pages, 8 figure

Dilepton production near partonic threshold in transversely polarized proton-antiproton collisions

It has recently been suggested that collisions of transversely polarized protons and antiprotons at the GSI could be used to determine the nucleon's transversity densities from measurements of the double-spin asymmetry for the Drell-Yan process. We analyze the role of higher-order perturbative QCD corrections in this kinematic regime, in terms of the available fixed-order contributions as well as of all-order soft-gluon resummations. We find that the combined perturbative corrections to the individual unpolarized and transversely polarized cross sections are large. We trace these large enhancements to soft gluon emission near partonic threshold, and we suggest that with a physically-motivated cut-off enhancements beyond lowest order are moderated relative to resummed perturbation theory, but still significant. The unpolarized dilepton cross section for the GSI kinematics may therefore provide information on the relation of perturbative and nonperturbative dynamics in hadronic scattering. The spin asymmetry turns out to be rather robust, relatively insensitive to higher orders, resummation, and the cut-offs.Comment: 23 pages, 19 figures as eps. Some discussion and references added. Final version to appear in Phys. Rev.