Semileptonic decays of pseudoscalar particles (M→M′+ℓ+νℓ) and short-distance behaviour of quantum chromodynamics

Abstract

Abstract The form factors which govern the semileptonic decays of pseudoscalar particles (M→M′+l+ ν l ) are constrained by the knowledge of the two-point function Π μν ( q ) = i ∫ d 4 x e iqx 〈0‖T V μ ( x ) V ν + (0)‖0〉 in the deep euclidean region, where V μ ( x ) denotes the vector current responsible for the transition M→M′. We derive the precise constraints from a QCD calculation of Π μν which includes perturbative contributions to two loops as well as leading non-perturbative contributions. Applications to π l3 , K l3 and D + → K 0 e + ν e decays are discussed.