Studies in QCD Modeling of Hadron Physics

Kent State University, Kent OH

Investigators

Abstract

0071361 Tandy Theoretical investigations of hadron properties and interactions will be carried out through a non-perturbative modeling of Quantum Chromodynamics (QCD), the strong interaction field theory of quarks and gluons. Specific topics to be addressed include: meson decays and meson interaction coupling constants and form factors, the mass and important decay modes of an exotic meson (rho-hat(1405) that is beyond the reach of the constituent quark model, issues beyond the ladder Bethe-Salpeter approximation and relevant for the masses and flavor mixing of eta and eta-prime mesons as well as the 3P0 scalar meson nonet, CP violating decays of hadrons, and hadron properties at finite temperature and baryon density. The work is aimed at providing a bridge between quark-gluon dynamics and effective hadron dynamics that will be necessary as experimental programs, such those at JLab and RHIC, probe nuclear interactions at a distance scale within the size of hadrons. The approach being followed is fully covariant, incorporates absolute quark confinement and dynamical chiral symmetry breaking, and implements solutions of the quark-antiquark Bethe-Salpeter equation directly in 4-space. The models of continuum QCD are guided by, and developed from, the truncated Dyson-Schwinger equations for the dressed propagators and vertex functions. Phenomenology enters through the modeling of the infrared form of the gluon two-point function. In the ultraviolet region, care is taken to preserve the one-loop renormalization group behavior of the running coupling. Parameters are fit to the low mass pseudoscalar meson properties. This produces a description of hadron observables in terms of quarks dressed with nonperturbative gluon effects. The distributed space-time extent of the meson modes is retained. Integral equation and eigenmode techniques are used in numerical investigations.