The recently published E865 data on charged K-e4 decays and pipi phases are reanalyzed to extract values of the two S-wave scattering lengths, of the subthreshold parameters alpha and beta, of the low-energy constants l_3 and l_4 as well as of the main two-flavour order parameters: < u-bar u > and F-pi in the limit m(u) = m(d) = 0 taken at the physical value of the strange quark mass. Our analysis is exclusively based on direct experimental information on pipi phases below 800 MeV and on the new solutions of the Roy equations by Ananthanarayan et al. The result is compared with the theoretical prediction relating 2 a_0^0 - 5 a_0^2 and the scalar radius of the pion, which was obtained in two-loop Chiral Perturbation Theory. A discrepancy at the 1-sigma level is found and commented upon.
Analysis and interpretation of new low-energy pi pi scattering data
GIRLANDA, Luca;
2002-01-01
Abstract
The recently published E865 data on charged K-e4 decays and pipi phases are reanalyzed to extract values of the two S-wave scattering lengths, of the subthreshold parameters alpha and beta, of the low-energy constants l_3 and l_4 as well as of the main two-flavour order parameters: < u-bar u > and F-pi in the limit m(u) = m(d) = 0 taken at the physical value of the strange quark mass. Our analysis is exclusively based on direct experimental information on pipi phases below 800 MeV and on the new solutions of the Roy equations by Ananthanarayan et al. The result is compared with the theoretical prediction relating 2 a_0^0 - 5 a_0^2 and the scalar radius of the pion, which was obtained in two-loop Chiral Perturbation Theory. A discrepancy at the 1-sigma level is found and commented upon.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
