The /ππ /Swave scattering lengths
Abstract
We match the known chiral perturbation theory representation of the /ππ scattering amplitude to two loops with a phenomenological description that relies on the Roy equations. On this basis, the corrections to Weinberg's low energy theorems for the /Swave scattering lengths are worked out to second order in the expansion in powers of the quark masses. The resulting predictions, a_{0}^{0}=0.220+/0.005, a_{0}^{2}=0.0444+/0.0010, contain remarkably small uncertainties and thus allow a very sensitive experimental test of the hypothesis that the quark condensate is the leading order parameter of the spontaneously broken chiral symmetry.
 Publication:

Physics Letters B
 Pub Date:
 September 2000
 DOI:
 10.1016/S03702693(00)008984
 arXiv:
 arXiv:hepph/0007112
 Bibcode:
 2000PhLB..488..261C
 Keywords:

 High Energy Physics  Phenomenology
 EPrint:
 12 pages, one figure