Graviton plus vector boson production to NLO in QCD at the LHC

We present the next-to-leading order QCD corrections to the associated production of the vector gauge boson (Z/W^±$Z/W^{\pm }$) and the graviton in the large extra dimension model at the LHC. We estimate the impact of the QCD corrections on the total cross sections as well as the differential distributions of the gauge bosons and find that they are significant. We also study the dependence of the cross sections on the arbitrary factorization scale and show the reduction in the scale uncertainties at NLO level. Further, we discuss the ultraviolet sensitivity of the theoretical predictions.     

Analytic,non-perturbative,gauge-invariant quantum chromodynamics: Nucleon scattering and binding potentials

Removal of the quenched approximation in the mechanism which produced an analytic estimate of quark-binding potentials, along with a reasonable conjecture of the color structure of the nucleon formed by such a binding potential, is shown to generate an effective nucleon scattering and binding potential. The mass-scale factor on the order of the pion mass, previously introduced to define the transverse imprecision of quark coordinates, is again used, while the strength of the potential is proportional to the square of a renormalized quantum chromodynamics (QCD) coupling constant. The potential so derived does not include corrections due to spin, angular momentum, nucleon structure, and electroweak interactions; rather, it is qualitative in nature, showing how Nuclear Physics can arise from fundamental QCD.     

Quark mass corrections to the perturbative thrust and its effect on the determination of αs

We consider the effects of quark masses to the perturbative thrust in e ⁺ e ⁻ annihilation. In particular we show that perturbative power corrections resulting from non-zero quark masses considerably alters the size of the non-perturbative power corrections and consequently, significantly changes the fitted value of α_s.     

Calculation of the Relativistic Correction in Terms of the Oscillator Representation

A procedure is proposed for the calculation of the corrections associated with the relativistic motion and spin interaction of particles in a system of a few bodies. The relativistic corrections for the Coulomb and Cornell potentials are determined from the relativistic generalization of the Schrödinger equation. The slope of the Regge trajectory and the masses of mesons are calculated taking the relativistic correction into account.     

QCD Correction to σ(e+e-→ZH→Zbb)

We study the QCD corrections to the calculated values of σ(e⁺e^-→ZH→Zbb), and find that for M_H<100 GeV, the process can be measured at the LEP energy to extract information of Higgs and the QCD corrections are negligible, namely the tree-level calculation is sufficiently aciurate for the energy range, while for M_H > 100 GeV, the Higgs-involved subprocess can only be investigated at NLC, and then the QCD correction becomes as large as 45%. For M_H > 2mt, considering the subprocess e⁺e^-→ZH→Ztt, the QCD corrections are also important and must be taken into account for the cross section evaluation.     

Spin polarization induced by an electric field in the presence of weak localization effects

We evaluate the spin polarization (Edelstein or inverse spin galvanic effect) and the spin Hall current induced by an applied electric field by including the weak localization corrections for a two-dimensional electron gas. We show that the weak localization effects yield logarithmic corrections to both the spin polarization conductivity relating the spin polarization and the electric field and to the spin Hall angle relating the spin and charge currents. The renormalization of both the spin polarization conductivity and the spin Hall angle combine to produce a zero correction to the total spin Hall conductivity as required by an exact identity. Suggestions for the experimental observation of the effect are given.     

Reprint of : Spin polarization induced by an electric field in the presence of weak localization effects

We evaluate the spin polarization (Edelstein or inverse spin galvanic effect) and the spin Hall current induced by an applied electric field by including the weak localization corrections for a two-dimensional electron gas. We show that the weak localization effects yield logarithmic corrections to both the spin polarization conductivity relating the spin polarization and the electric field and to the spin Hall angle relating the spin and charge currents. The renormalization of both the spin polarization conductivity and the spin Hall angle combine to produce a zero correction to the total spin Hall conductivity as required by an exact identity. Suggestions for the experimental observation of the effect are given.     

Nonfactorizable B→xcoK Decay and QCD Factorization

We study the unexpectedly large rate for the factorization-forbidden decay B→χ_c0K within the QCD factorization approach. We use a non-zero gluon mass to regularize the infrared divergences in vertex corrections. The end-point singularities arising from spectator corrections are regularized and carefully estimated by the off-shellness of quarks. We find that the contributions arising from the vertex and leading-twist spectator corrections are numerically small, and the twist-3 spectator contribution with chiral enhancement and linear end-point singularity becomes dominant. With reasonable choices for the parameters, the branching ratio for B→χ_c0K decay is estimated to be in the range (2～4)×10^-4, which is compatible with the Belle and BaBar data.     

在格点上构造计算胶球质量的新途径

发展了一种为了计算胶球质量而构造格点算符的新途径.基于所选用算符的连续极限与状态量子数JPC两者之间的联系,状态的自旋就可以在数值模拟中唯一和直接地被确定下来.进而,这一途径可以被应用于计算任意自旋J的胶球质量.在淬火近似下,给出在SU(3)纯规范场中0⁺⁺态和2⁺⁺态胶球质量的初步结果,它们分别是1754(85)(86)MeV和2417(56)(117)MeV.     

Exotic and excited-state meson spectroscopy and radiative transitions from lattice QCD

We discuss recent progress in extracting the excited meson spectrum and radiative transition form factors from lattice QCD.We mention results in the charmonium sector,including the first lattice QCD calculation of radiative transition rates involving excited charmonium states,highlighting results for high spin and exotic states.We present recent results on a highly excited isovector meson spectrum from dynamical anisotropic lattices.Using carefully constructed operators we show how the continuum spin of extracted states can be reliably identified and confidently extract excited states,states with exotic quantum numbers and states of high spin.This spectrum includes the first spin-four state extracted from lattice QCD.We conclude with some comments on future prospects.     

Spin freezing in geometrically frustrated β-Mn probed by muon spin relaxation

Muon spin relaxation was measured down to 0.05 K on a geometrically frustrated metallic system, β-Mn. The observed relaxation rate increases with decreasing temperature and unexpectedly makes a peak at 0.5 K indicating a spin freezing below the temperature. Actually the asymmetry is almost recovered by applying a longitudinal magnetic field of 0.1 T. But since the tail amplitude is more than half and the dynamical relaxation is still appreciable at the lowest temperature, it is likely that the frozen moments are associated with imperfection as oxygen impurity and the intrinsic ground state is fluctuating spin liquid. This revised version was published online in August 2006 with corrections to the Cover Date.     

Localization corrections to charge and spin conductivity in ferromagnetic layered structures

Localization corrections to charge and spin conductivity of two-dimensional ferromagnetic systems with spin–orbit interaction are studied theoretically. The corrections lead to negative magnetoresistance — also in the presence of spin–orbit scattering. Magnitude of the corrections depends on the magnetization orientation with respect to the plane of the system. The corrections to spin conductivity are shown to be small.     

Transverse spin structure of hadrons from lattice QCD

This paper presents recent lattice QCD calculations of transverse spin densities of quarks in hadrons.² Based on our simulation results for the tensor generalized form factors, we find substantial correlations between spin and coordinate degrees of freedom in the nucleon and the pion. They lead to strongly distorted transverse spin densities of quarks in the nucleon and a surprisingly non-trivial transverse spin structure of the pion. Following recent arguments by Burkardt [M. Burkardt, Phys. Rev. D 72 (2005) 094020], our results imply that the Boer-Mulders function , describing correlations of the transverse spin and intrinsic transverse momentum of quarks, is large and negative for up-quarks in the proton and the π⁺. This supports the recent hypothesis that all Boer-Mulders functions are alike [arXiv:0705.1573], and also provides additional motivation for future studies of azimuthal asymmetries in πp Drell-Yan production at, e.g., COMPASS.     

Higher Twist Effects in Hadronic B Decays

Within the framework of QCD factorization, we discuss various important corrections arising from higher twist distribution amplitudes of mesons in the hadronic B decays.     

Analytical approach for the approximate solution of the longitudinal structure function with respect to the GLR-MQ equation at small x

We show that the nonlinear corrections to the longitudinal structure function can be tamed the singularity behavior at low x values, with respect to GLR-MQ equations. This approach can determined the shadowing longitudinal structure function based on the shadowing corrections to the gluon and singlet quark structure functions. Comparing our results with HERA data show that at very low x this behavior completely tamed by these corrections.     

Beam polarization effects on top-pair production at the ILC

Full one-loop electroweak corrections for an \(e^-e^+\rightarrow t \bar{t}\) process associated with sequential \(t\rightarrow b \mu \nu _\mu \) decay are discussed. At the one-loop level, the spin-polarization effects of the initial electron and positron beams are included in the total and differential cross sections. A narrow-width approximation is used to treat the top-quark production and decay while including full spin correlations between them. We observed that the radiative corrections due to the weak interaction have a large polarization dependence on both the total and the differential cross sections. Therefore, experimental observables that depend on angular distributions such as the forward–backward asymmetry of the top-production angle must be treated carefully including radiative corrections. We also observed that the energy distribution of bottom quarks is largely affected by the radiative corrections.     

Improved Gell-Mann-Okubo Relations and SU(3) Rotation Excitations of Baryon States

The corrections to the Gell-Mann-Okubo relations of baryon masses are presented in the SU(3) Skyrrne model. These corrections are calculated up to the second order in flavor breaking at the skyrmion quantum mechanics. The results are compatible with the experimental data. They could be regarded as a signal of existence of the SU(3) rotation excitation states of baryons: 27-let (with spin 1/2 or 3/2), 10^*-let (with spin 1/2) and 35-let (with spin 3/2).     

Electroweak corrections to the observables of W-boson production at RHIC

The processes of the single W-production in hadron-hadron collisions are suggested for investigation of the nucleon spin. An approach is proposed for the determination of quark spin densities at low x. The lowest order electroweak radiative corrections to the observable quantities are calculated. The numerical calculations of the cross sections and the single spin asymmetries taking into consideration the electroweak corrections at RHIC energies have been made.     

SUSY-QCD Effects in Top Quark Pair Production in Association with a Gluon at the ILC

Given the null results of searches for new physics at the LHC, we investigate the one-loop effects SUSY QCD in the process e⁺e^-→ttg at the ILC in Minimal Supersymmetric Standard Model (MSSM). We find that the relative SUSY-QCD corrections to the cross section of e⁺e^-→ttg can maximally reach 6.5%(3.2%) at the ILC with √s=1000 GeV when m=313:4 GeV and m=500(1500) GeV.     

Theory of hadron-deuteron elastic scattering in the GeV region

A multiple scattering formalism for the medium energy hadron-deuteron elastic scattering is developed. This approach provides an extension of the Glauber theory incorporating the complete spin structure and the corrections to the eikonal and fixed scatterer approximations. The systematics of the spin observables and their relation to the hadron-deuteron as well as to hadron-nucleon amplitudes are discussed. An approximate cancellation between few corrections to the double scattering term is found which leaves the non-eikonal correction as the dominant one, and often, very important numerically, e.g., in the deuteron tensor polarization. Comparison of the parameter-free predictions of the theory based on the recent NN phase shift amplitudes with the data on polarization observables in pd elastic scattering is made.