STANDARD VERSUS GENERALIZED CHIRAL PERTURBATION-THEORY - THE CHELL-OLSSON TEST

A way of testing the pi pi predictions of chiral perturbation theory a gainst experimental data is to use dispersion relations to continue ex perimental information into the subthreshold region where the theory s hould unambiguously apply. Chell and Olsson have proposed a test of th e subthreshold behavior of chiral expansions which highlights potentia l differences between the standard and the generalized forms of the th eory. We illustrate how, with current experimental uncertainties, data cannot distinguish between these particular discriminatory coefficien ts despite their sensitivity. Nevertheless, the Chell-Olsson test does provide a consistency check of the chiral expansion, requiring that t he O(p(6)) corrections to the discriminatory coefficients in the stand ard theory must be similar to 100%. Indeed, some of these have been de duced from the new O(p(6)) computations and found to give such large c orrections. One can thm check that the O(p(8)) corrections must be muc h smaller. We conclude that this test, like others, cannot distinguish between the different forms of chiral symmetry breaking embodied in t he alternative versions of chiral perturbation theory without much mor e precise experimental information near threshold.