RHO-MESON PROPERTIES IN THE NAMBU-JONA-LASINIO MODEL

Some properties of the rho vector meson are calculated within the Namb u-Jona-Lasinio model, including processes that go beyond the random ph ase approximation. To classify the higher order contributions, we adop t 1/N-c as expansion parameter. In particular, we evaluate the leading order contributions to the rho --> pi pi decay width, obtaining the v alue 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.