Chiral symmetry amplitudes in the S-wave isoscalar and isovector channels and the sigma, f_0(980), a_0(980) scalar mesons (HADRON'97)

Abstract

We use a non-perturbative approach which combines coupled channel Lippmann-Schwinger equations with meson-meson potentials provided by the lowest order chiral Lagrangian. By means of one parameter, a cut off in the momentum of the loop integrals, which results of the order of 1 GeV, we obtain singularities in the S-wave amplitudes corresponding to the sigma, f_0 and a_0 resonances. The \pi\pi --> \pi\pi, \pi\pi --> K bar(K) phase shifts and inelasticities in the T=0 scalar channel are well reproduced as well as the \pi^0 eta and K bar(K) mass distributions in the T=1 channel. Furthermore, the total and partial strong decay widths of the f_0 and a_0 resonances are properly reproduced.