We investigate the spin correlations in top quark pair production near threshold at the e−e+ linear collider. Comparing with the results above the threshold region, we find that near the threshold region the off-diagonal basis, the optimized decomposition of the top quark spins above the threshold region, does not exist, and the beamline basis is the optimal basis, in which there are the domina...

Using some simple .ass.mptions, we present in this paper a calculation of the quark fragmentation functions seen in deep inelastic processes. The results provide evidence for the conjecture that both jets seen in high p1 reactions at the ISR stem from similar parents. The calculated functions are in excellent agreement with the inclusive distributions seen in vp and tp scattering,and in particu...

A model for dihadron fragmentation functions is briefly outlined, that describes the fragmentation of a quark in two unpolarized hadrons. The parameters are tuned to the output of the PYTHIA event generator for two-hadron semi-inclusive production in deep inelastic scattering at HERMES. Then predictions are made for the unknown polarized fragmentation function and the related single-spin asymme...

It is shown that neutrino and antineutrino deep inelastic scattering of unpolarized and polarized Λ and Λ productions, can provide a clean separation of unpolarized and polarized fragmentation functions of a quark into a Λ, for both light-flavor quarks and antiquarks and also for strange quarks. Combining with Λ and Λ productions, in polarized electron deep inelastic scattering, one can systema...

Improvements of the Kogut-Susskind quark action may allow extraction of continuum physics from coarser lattices than would be required with the simplest formulation. This is especially important for full QCD simulations, which are much more time consuming than quenched calculations. Improvement of the rotational symmetry and the dispersion relation can be achieved by introducing the Naik term, ...

We study the role of the nucleon resonances (N *) in ω photoproduction by using the quark model resonance parameters predicted by Capstick and Roberts. The employed γN → N * and N * → ωN amplitudes include the configuration mixing effects due to the residual quark-quark interactions. The contributions from the nucleon resonances are found to be important in the differential cross sections at la...

Instanton-induced deep-inelastic processes are considered. Unlike previous results we calculate nonzero quark modes contribution. As was shown [1], QCD-instantons can appear at the intermediate stage of deep inelastic scattering (DIS) and be, in principle, observed at HERA (DESY) [2, 3]. Specifically, instantons can be produced in quark-gluon subprocess (Fig.1).