Exchange Current and Leptonic Decays of Baryons in the Quark Model

Abstract

Contributions of meson exchange currents to leptonic decays of baryons are investigated within framework of quark model based on same line of thought of our previous papers, in which exchange magnetic moment and decays of decuplet baryons are studied. It is shown in present paper that meson exchange current among constituent quarks gives little effects on leptonic decays of baryons. The main contribution to axial vector part comes from a pseudoscalar meson exchange current, while a pseudoscalar-vector meson exchange current contributes to vector part. Their contributions are, indeed, so small that the property of quarks is shown to be a good approximation. In pa~ticular, in neutron j3-decay exchange- currents give only a little contribution and relation GAIGv = -5/3 obtained from additivity assumption cannot be improved.