PION OBSERVABLES IN THE EXTENDED NJL MODEL WITH VECTOR AND AXIAL-VECTOR MESONS

The momentum-space bosonization method of a Nambu and Jona-Lasinio typ e model with vector and axial-vector mesons is applied to pi pi scatte ring. Unlike the case in earlier published papers, we obtain the pi pi scattering amplitude using the linear and nonlinear realizations of c hiral symmetry and Fully taking into account the momentum dependence o i meson vertices. We show the full physical equivalence between these two approaches. The chiral expansion procedure in this model is discus sed in detail. Chiral expansions of the quark mass, pion mass and cons tant f(pi) are obtained. The low-energy pi pi phase shifts are compare d to the available data. We also study the scalar form factor of the p ion. (C) 1996 Academic Press, Inc.