Phenomenological analysis of a fixed-sphere bag model

Abstract

We perform a phenomenological analysis of baryon matrix elements in a fixed-sphere MIT bag model. The model consists of massive, noninteracting quarks which carry the usual SU(3) quantum numbers as well as an SU(3) of color. Two-quark matrix elements investigated include those of the $\sigma$ operator and axial-vector and vector currents and the magnetic moment, charge radius, and dipole moments of the electromagnetic current. Among our results are the masses 44 MeV for nonstrange quarks and 298 MeV for strange quarks. The model is successful in predicting static properties of the lowest-mass baryons, but has a problem in describing the radiative decay of the nucleon resonance, $N_{}^{*}{}_{13}{}^{}\mathrm{}\left(1520\right)\mathrm{}$. Four-quark matrix elements parity-violating nonleptonic decay amplitudes of the ${\frac{1}{2}}^{+}$ baryons, are investigated and are found to be poorly described by the model.