Comment on the prediction of two-loop standard chiral perturbation theory for low-energy ππ scattering

Four of the six parameters defining the two-loop ππ scattering amplitude have been determined using Roy dispersion relations. Combining this information with the Standard χPT expressions, the threshold parameters, low-energy phases and the O(p4) constants l1r, l2r are obtained. The result reproduces the correct D-waves but it is incompatible with existing Standard χPT analyses of K14 form factors beyond one loop. (author)