Two loop calculation of the ω-ρ mass splitting

A nonlocal Nambu--Jona-Lasinio model is used to calculate strong interaction contributions to the {ω}-{ρ} mass splitting. We analyze the contributions of the {ρ}{→}{π}{π}, {ω}{→}{ρ}{π}, and {ω}{→}{π}{π}{π} self-energy diagrams and fully account for their momentum dependence. We determine that, of these, the {ρ}{→}{π}{π} term dominates to the point where the other terms may be neglected. The meson loop expansion in this model is therefore seen to be rapidly convergent. The results of our calculation suggest some qualitative constraints on the confining part of the q-q{} interaction in models of this type.