Ua(1) breaking effects on the light scalar meson spectrum

Abstract

Effects of the UA(1) breaking interaction on the low-lying nonet scalar mesons are studied using the extended Nambu-Jona-Lasinio model. The strength of the UA(1) breaking interaction is determined by the electromagnetic decays of the η meson. We find that the UA(1) breaking interaction gives rise to about 150 MeV mass difference between the σ and a0 mesons. We also find that the strangeness content in the σ meson is about 15%. The calculated mass of the I = 1/2 state is about 200 MeV heavier than that of the I = 1 state. The order of these masses is not likely to change within this model.