Kℓ4 form-factors and π – π scattering

Abstract The F and G form-factors of K l4 and the quark condensates are calculated to O (p 6 ) in Chiral Perturbation theory (CHPT). Full formulas are presented as much as possible. A full refit of most of the O (p 4 ) CHPT parameters is done with a discussion of all inputs and underlying assumptions. We discuss the consequences for the vacuum expectation values, decay constants, pseudoscalar masses and π – π scattering.