  Effects of the U_A(1) breaking interaction on the low-lying nonet scalar
mesons are studied using the extended Nambu-Jona-Lasinio model. The strength of
the U_A(1) breaking interaction is determined by the electromagnetic decays of
the eta meson. We find that the U_A(1) breaking interaction gives rise to about
150 MeV mass difference between the sigma and a_0 mesons. We also find that the
strangeness content in the \sigma 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.
