The constraints of unitary on pi pi scattering dispersion relations

A new dispersion relation for the partial wave pipi scattering S matrix is set up. Using the dispersion relation we generalize the single channel unitarity condition, SS+ = 1, to the entire complex s plane, which is equivalent to the generalized unitarity condition in quantum mechanics. The pole positions of the sigma resonance and the f(o)(980) resonance are estimated based on the theoretical relations we obtained. The central value of the sigma pole position is M-sigma similar or equal to 410 MeV, Gamma(sigma) similar or equal to 550 MeV, obtained after including the constraint of the Adler zero condition. (C) 2002 Elsevier Science B.V. All rights reserved.Physics, MultidisciplinarySCI(E)15ARTICLE1-259-6653