Rho meson properties in the NJL model

Some properties of the rho vector meson are calculated within the Nambu-JonaLasinio model. including processes that go beyond the random phase approximation. To classify the higher order contributions. we adopt 1/N-c as expansion parameter. In particular, we evaluate the leading order contributions to the rho --> pi pi decay width, obtaining the value Gamma = 118 MeV, and to the shift of the rho mass which turns out to be lowered by 64 MeV with respect to its RPA value. A set of model parameters is determined accordingly.