The decay τ→3πντ as a probe of the mechanism of dynamical chiral symmetry breaking Original Research Article

The decays τ→3π+ντ are analyzed at one loop order in the framework of Generalized Chiral Perturbation Theory, in order to test the sensitivity to the size of spontaneous chiral symmetry breaking parameters, contained in the S-wave. The latter, due to a kinematical suppression, at threshold, of the P-wave, is relatively large enough to be detectable at high-energy machines, through azimuthal left-right asymmetries. This quantity (for the π−π−π+ mode), integrated from threshold to Q2=0.35 GeV2, varies from (17±3)% in the standard case of large condensate up to (40±5)% in the extreme case of tiny condensate. The feasibility of such measurement at high luminosity colliders (e.g., CLEO) is discussed. This method provides an independent cross-check of forthcoming experimental determination of the two-light-flavor chiral condensate, based on low-energy ππ scattering.