Chiral coupling constants (l)over-bar(1) and (l)over-bar(2) from pi pi phase shifts

A Roy equation analysis of the available pi pi phase shift data is performed with the I=0 S-wave scattering length a(0)(0) in the range predicted by the one-loop standard chiral perturbation theory. A suitable dispersive framework is developed to extract the chiral coupling constants <(l)over bar (1)>, <(l)over bar (2)> and yields <(l)over bar (1)>=-1.70+/-0.15 and <(l)over bar (2)>approximate to 5.0. We remark on the implications of this determination to (combinations of) threshold parameter predictions of the three lowest partial waves.