The quark Dyson-Schwinger equation and meson Bethe-Salpeter equation are studied in a truncation scheme that extends the rainbow-ladder approximation such that, in the chiral limit, the isovector, pseudoscalar meson remains massless. Quarkquark (diquark) correlations, which are bound in rainbow-ladder approximation, are destabilised by repulsive contributions that only appear at higher order in...

The reduced Bethe-Salpeter equation with scalar confinement and vector gluon exchange is applied to quark-antiquark bound states. The so called intrinsic flaw of Salpeter equation with static scalar confinement is investigated. The notorious problem of narrow level spacings is found to be remedied by taking into consideration the retardation effect of scalar confinement. Good fit for the mass s...

This is the user manual for the software package BSEPACK (Bethe--Salpeter Eigenvalue Solver Package).

The neutron structure function F n 2 (x) is evaluated within the kinematic range 10−3 < x < 1 from the deuteron and proton data by employing relativistic theoretical description of FD 2 (x) and several assumptions on the high-x asymptotics of F n 2 (x)/F p 2 (x). It is shown that new measurements of F D 2 (x) in the range 0.6 < x ≤ 0.8 would substantially improve understanding of the relation b...

The spinless Salpeter equation is the combination of relativistic kinematics with some static interaction potential. The nonlocal nature of the Hamiltonian resulting from this approximation renders difficult to obtain rigorous analytic statements on resulting solutions. In view of this unsatisfactory state of affairs, we calculate analytic upper bounds on the involved energy levels, and, for th...

We extend to regular QCD the derivation of a confining qq̄ Bethe–Salpeter equation previously given for the simplest model of scalar QCD in which quarks are treated as spinless particles. We start from the same assumptions on the Wilson loop integral already adopted in the derivation of a semirelativistic heavy quark potential. We show that, by standard approximations, an effective meson squared...