Remarks on the Strong Coupling Constants in Heavy Hadron Chiral Lagrangians

Abstract

In the heavy quark limit, there are three independent strong axial coupling constants in chiral Lagrangians for ground-state heavy hadrons: g in the meson sector, and g_1, g_2 in the baryon sector. The coupling g_2 is extracted from recent CLEO measurements of $\Sigma_c^*\to\Lambda_c\pi$ to be $|g_2|=0.57\pm 0.10$, in agreement with the nonrelativistic quark model expectation but in $2\sigma$ deviation from the large-N_c argument. The parameter g_1 cannot be determined directly from strong decays of heavy baryons. Nevertheless, some information of g_1 can be learned from the radiative decay $\Xi_c^{'*0}\to\Xi_c^0\gamma$, which is prohibited at tree level by SU(3) symmetry but induced by chiral loops. A measurement of $\Gamma(\Xi_c^{'*0}\to\Xi_c^0\gamma)$ will yield two possible solutions for g_1. Assuming the validity of the quark model relations among different coupling constants, the experimental value of g_2 implies that $|g|=0.70\pm 0.12$ and $|g_1|=0.93\pm 0.16$.