THE CHARMED STRANGE MESON SYSTEM

Motivated by the recent surprising discovery of two new meson states with [Formula: see text] quark content but unexpectedly low masses and narrow total decay widths, we work out, in a nonrelativistic potential-model approach developed already some two decades ago, the predictions for the energy levels of the corresponding charm–anti-strange quark bound states. In spite of the fact that this simple quark model reproduces the mass spectrum of the previously observed hadrons remarkably well, we are led to the conclusion that, without considerable modifications, both the new states do not fit into this framework.

MASSES, MAGNETIC MOMENTS, AND SEMILEPTONIC DECAYS OF SPIN-1/2 BARYONS WITH SEA CONTRIBUTION

The spin-1/2 baryons are pictured as a composite system made out of a "core" of three valence quarks (as in the simple quark model) surrounded by a "sea" (of gluon and [Formula: see text] pairs) which is specified by its total quantum numbers. We assume that the sea is an SU(3) flavor octet with spin 0 or 1 but no color. This model, considered earlier, is used to obtain simultaneous fits for masses, magnetic moments and GA/GV for semileptonic decays. These fits give predictions for nucleon spin distributions in reasonable agreement with experiment.

SUBSTRUCTURE EFFECT ON ρ-ω MIXING IN CHARGE-SYMMETRY VIOLATION

In generating a charge-symmetry breaking potential using ρ-ω mixing it is usually assumed that the mixing amplitude is constant (at the on-mass-shell value). Since the exchanged meson is actually far off-shell one must question the validity of this assumption. By constructing a simple quark model in which the mixing is generated by the u-d quark mass difference, we find that the assumption seems to be a very poor one.