The phase of the sigma -> pi-pi amplitude in J/Psi -> omega-pi-pi

Abstract

The phase variation of the sigma -> pi-pi amplitude is accurately determined as a function of mass from BES II data for J/Psi -> omega-pi-pi. The determination arises from interference with the strong b1(1235)-pi amplitude. The observed phase variation agrees within errors with that in pi-pi elastic scattering.Comment: 10 pages, 4 figures, Euro. Phys. J C (in press