The Constituent Chiral Quark Model Revisited

Abstract

We reconsider the Constituent Chiral Quark Model of Manohar and Georgi in the presence of $SU(3)_{L}\times SU(3)_{R}$ external sources. As recently emphasized by Weinberg, the corresponding effective Lagrangian is renormalizable in the Large--${\rm N_c}$ limit. We show, however, that the number of the required counterterms depends crucially on the value of $g_A$ and it is minimized for $g_A =1$. We then find that with a rather small value for the constituent quark mass, which we fix phenomenologically to $M_Q =(190\pm 40)\MeV$, the model reproduces rather well the values of several well known low energy constants. We also comment on the limitations of the model as well as on a few {\it exceptional} applications, to more complicated low--energy observables, where one can expect the model to make reasonably good predictions.