Effective chiral meson Lagrangian for the extended Nambu-Jona-Lasinio model - art. no. 114013

We present a derivation of the low-energy effective meson Lagrangian of the extended Nambu-Jona-Lasinio (ENJL) model. The case with a linear realizati on of broken SU(2) X SU(2) chiral symmetry is considered. There are two cru cial points why this revision is needed. First, it is thr Explicit chiral s ymmetry breaking effect. On the basis of symmetry arguments we show that re levant contributions related with the current quark mass terms are absent f rom the effective Lagrangians derived so far in the literature. Secondly we suggest a chiral covariant way to avoid the nondiagonal terms responsible for the pseudoscalar-axial-vector mixing from the effective meson Lagrangia n. In the framework of the linear approach this diagonalization has not bee n done correctly. We discuss as well the SU(2) X SU(2)/SU(2) coset space pa rametrization for the revised Lagrangian (nonlinear ansatz). Our Lagrangian differs in an essential way from those that have been derived until now on the basis of both linear and nonlinear realizations of chiral symmetry.