Pionic Decays of Hadrons and the Coupling of Pions to Quarks

Abstract

The pion decay rates of excited heavy-light flavor mesons states can provide direct information on the coupling of pions to light-flavor constituent quarks because pions only couple to their light flavor constituent. The chiral quark model describes the empirical widths of excited D-mesons fairly satisfactorily. In this model the pion coupling is determined by the axial coupling of the light flavor quarks. The reaction D ^* _s → D _s π⁰ provides information on the η-meson coupling to strange constituent quarks, as it is mediated by π⁰ - η mixing. The two pion decay rates of heavy quarkonia implies pion exchange between heavy quarks and antiquarks, which is phenomenologically significant.