Sigma, Kappa, fo(980) and a0(980)

Abstract

Both sigma and kappa are well established from E791 data on D->3pi and Ds->Kpipi and BES II data on J/Psi -> omega pi pi and KKpipi. These fits are accurately consistent with pipi and Kpi elastic scattering when one allows for the Adler zero which arises from Chiral Symmetry Breaking. The phase variation with mass is consistent between elastic scattering and production data. Possible interpretations of sigma, kappa, fo(980) and ao(980) are explored. The experimental ratio g^2(fo(980)->KK)/g^2(ao(980)->KK) = 2.7+-0.5 suggests strongly that fo(980) has a large KK component in its wave function. This is a natural consequence of its pole lying very close to the KK threshold.