DIRAC SEA EFFECTS IN A LINEAR SIGMA-MODEL WITH VECTOR AND AXIAL-VECTOR FIELDS

We propose a new approach to collective phenomena in a linear sigma mo del which includes classical vector-isovector and pseudovector-isovect or fields. The main purpose is to describe meson modes composed of two ingredients: phenomenological structureless fields and q ($) over bar q excitations of the vacuum. This procedure, performed in the context of many-body techniques, provides a natural renormalization process t hrough the q ($) over bar q excitations.