EFFECTIVE LAGRANGIANS FROM CHIRAL QUARK DYNAMICS

The spontaneously broken chiral symmetry scenario of quantum chromo-dynamics (QCD) together with the Veltman theorem implies that the low energy effective Lagrangian, of QCD must be of the nonliear σ model type. The effective Lagrangians resulting from integrating the quark fields from the gauged or nongauged chiral quark model Lagrangian in a Skyrme-type scenario may be completely equivalent to QCD in the large N_c limit at low energy and therefore may serve as realistic models for low energy hadron dynamics. For this purpose, we present in detail the recent development of the effective action expansion, in particular the evaluation of the fermion determinant of these models. The implications on the low energy phenomenology associated with these effective Lagrangians will be discussed.