Modern Physics Letters A

We review the calculation of moments of both the polarized and unpolarized parton distribution functions of the nucleon in lattice QCD, and in particular their extrapolation to the physical region. We also discuss the reconstruction of the x dependence of the valence quark distributions in the nucleon from a finite number of lattice moments.

We review the attempts to construct black hole/string solutions in asymptotically plane wave spacetimes. First, we demonstrate that geometries admitting a covariantly constant null Killing vector cannot admit event horizons, which implies that pp-waves cannot describe black holes. However, relaxing the symmetry requirements allows us to generate solutions which do possess regular event horizons while retaining the requisite asymptotic properties. In particular, we present two solution generating techniques and use them to construct asymptotically plane wave black string/brane geometries.

The contributions of δ-isovector-scalar and ρ-isovector-vector meson-exchanges to nucleon–nucleon elastic cross-sections (ECS) are studied based on QHD-type effective Lagrangian within the framework of the RBUU transport theory. The detailed expressions of ECS for symmetric nuclear system have also obtained. The medium correction of ρ-meson mass and a proper symmetry energy coefficient are selected in order to fix a set of suitable coupling constants for δ and ρ exchanges with the constraint of free ECS as a function of energy. The respective δ and ρ contributions to free ECS as a function of energy are also shown and it is found they both affect the neutron–proton and neutron–neutron (proton–proton) ECS on the contrary way.

We have studied the generalised Brans–Dicke theory and obtained exact solutions of a(t), ϕ(t) and ω(t) for different epochs of the cosmic evolution. We discuss how inflation, deceleration, cosmic acceleration can result from this solution. The time variation of G(t) is also examined.

We investigate the CP violating asymmetry, the forward backward asymmetry and the CP violating asymmetry in the forward–backward asymmetry for the inclusive B → X_dℓ⁺ℓ^- decays for the ℓ = e,μ,τ channels in the standard model. It is observed that these asymmetries are quite sizeable and B → X_dℓ⁺ℓ^- decays seem promising for investigating CP violation.

We give a proof of a local relation between the inverse Faddeev–Popov operator and the non-Abelian Coulomb interaction between color charges.

We formulate quantum mechanics in the two-dimensional torus without using position operators. We define an algebra with only momentum operators and shift operators and construct an irreducible representation of the algebra. We show that it realizes quantum mechanics of a charged particle in a uniform magnetic field and prove that any irreducible representation of the algebra is unitarily equivalent to each other. This work provides a firm foundation for the noncommutative torus theory.