We calculate the soft contribution to high energy quark-quark scattering that arises from an instanton-induced quark anomalous chromomagnetic moment. We demonstrate that this is a large contribution, which cannot be neglected for transverse momenta of a few GeV. We discuss the influence of this effect on inclusive particle production. [email protected]

We study the possibility that the light scalar mesons are q̄q states rather than q̄q. We perform a lattice QCD calculation of pseudoscalar meson scattering amplitudes, ignoring quark loops and quark annihilation, and find indications that for sufficiently heavy quarks there is a stable four-quark bound state with J = 0 and non-exotic flavor quantum numbers.

The formal light-cone properties of commutators involving current divergences are studied in the gluon model. Relations are derived which make it possible (in principle) to distinguish the vector from the (pseudo) scalar gluon model. In the vector gluon model these relations provide an experimental determination of the bare quark masses. The additional assumption that the residues of any a! = 0...

One of the key elements to understanding the structure of the nucleon is the role of its quark-antiquark sea in its ground state properties such as charge, mass, magnetism and spin. In the last decade, parity-violating electron scattering has emerged as an important tool in this area, because of its ability to isolate the contribution of strange quark-antiquark pairs to the nucleon's charge and...

We study how the quasiparticle picture of the quark can be modified near but above the critical tempearture (Tc) of the chiral phase transition; we incorporate into the quark self-energy the effects of the precursory soft modes of the phase transition, i.e., ‘para-σ(π) meson’. It is found that the quark spectrum has a three-peak structure near Tc: We show that the additional new spectra origina...