Baryon-Meson Couplings in the $q\bar{q}$ Pair-Creation Quark Model. I

Abstract

Characteristic features of the baryon-meson coupling vertices are studied in terms of a quark model in which quark-antiquark pair-creation processes inherent in the quark-gluon interaction Lagrangian are explicitly incorporated. It is shown that the standard non-relativistic baryon-meson vertex functions are naturally derived from quark exchange diagrams in a way that approximate SU6 relations are apparently satisfied for the coupling constants. Under the assumption of the flavor SU3 symmetry, this formalism yields a simple analytic expression for the coupling constants of S-wave baryons, which contains only one parameter related to the overall strength. The model predictions are examined in conjunction with the available empirical information. The effect of flavor symmetry breaking is also discussed with respect to the pion decay widths of decuplet baryons. Due to the improper treatment of the chiral symmetry in constituent quark models, all the pion coupling constants are universally too small by factor 3 ∼6 in strength.