B.K. Jennings

Role of color neutrality in nuclear physics: Modifications of nucleonic wave functions

The influence of the nuclear medium upon the internal structure of a composite nucleon is examined. The interaction with the medium is assumed to depend on the relative distances between the quarks in the nucleon consistent with the notion of color neutrality, and to be proportional to the nucleon density. In the resulting description the nucleon in matter is a superposition of the ground state (free nucleon) and radial excitations. The effects of the nuclear medium on the electromagnetic and weak nucleon form factors and the nucleon structure function are computed using a light-front constituent quark model. Further experimental consequences are examined by considering the electromagnetic nuclear response functions. The effects of color neutrality supply small but significant corrections to predictions of observables. {copyright} {ital 1996 The American Physical Society.}

A Relativistic meson exchange model of pion - nucleon scattering

Abstract A relativistic meson exchange approach to the pion-nucleon interaction is developed using a three-dimensional relativistic two-body propagator and the results using different propagators compared. The relativistic approach is able to describe low-energy scattering up to 400 MeV above threshold, while preserving the soft-pion theorems. The different propagators give similar results, as the form factors necessary to get a fit suppress much of the multiple scattering.

Z* resonances: Phenomenology and models

We explore the phenomenology of, and models for, the

On color transparency

{Z}^{*}

Recovering relativistic nuclear phenomenology from the quark-meson coupling model☆

resonances, the lowest of which is now well established, and called the

Modified quark - meson coupling model for nuclear matter

\ensuremath{\Theta}.

Asymmetries in the weak decay of polarized hypernuclei

We provide an overview of three models which have been proposed to explain its existence and/or its small width, and point out other relevant predictions and potential problems, for each. The relation to what is known about KN scattering, including possible resonance signals in other channels, is also discussed.

Kaon-nucleon scattering in an extended cloudy bag model

Abstract A quantum mechanical treatment of high momentum transfer nuclear processes is presented. Color transparency, the suppression of initial and final state interaction effects, is shown to arise from using the closure approximation. New conditions for the appearance of color transparency are derived.

The Dirac equation and Λ-nucleus systematics

The quark-meson coupling (QMC) model for nuclear matter, which describes nuclear matter as non-overlapping MIT bags bound by the self-consistent exchange of scalar and vector mesons is modified by the introduction of a density dependent bag constant. It is found that when the bag constant is significantly reduced in nuclear medium with respect to its free space value, large canceling isoscalar Lorentz scalar and vector potentials for the nucleon in nuclear matter emerge naturally. Such potentials are comparable to those suggested by relativistic nuclear phenomenology. This suggests that the modification of the bag constant in the nuclear medium may play an important role in low- and medium-energy nuclear physics.

Smooth relativistic two-body propagators

The quark-meson coupling model for nuclear matter, which describes nuclear matter as nonoverlapping MIT bags bound by the self-consistent exchange of scalar and vector mesons, is modified by introducing medium modification of the bag constant. We model the density dependence of the bag constant in two different ways: One invokes a direct coupling of the bag constant to the scalar meson field, and the other relates the bag constant to the in-medium nucleon mass. Both models feature a decreasing bag constant with increasing density. We find that when the bag constant is significantly reduced in nuclear medium with respect to its free-space value, large canceling isoscalar Lorentz scalar and vector potentials for the nucleon in nuclear matter emerge naturally. Such potentials are comparable to those suggested by relativistic nuclear phenomenology and finite-density QCD sum rules. This suggests that the reduction of bag constant in nuclear medium may play an important role in low- and medium-energy nuclear physics. {copyright} {ital 1996 The American Physical Society.}