Abstract

We use the Mellin-Barnes representation in order to improve the theoretical estimate of mass corrections to the width of light pseudoscalar meson decays into a lepton pair, P ? l+ l-. The full resummation of the terms (M2 / ?2)n, (m2 / M2)n and (m2 / ?2)n to the decay amplitude is performed, where m is the lepton mass, M is the meson mass and ? ˜ m? is the characteristic scale of the P ? ?* ?* form factor. The total effect of mass corrections is quite important for ? (?') decays. We also comment on the estimation of the hadronic light-by-light scattering contribution to the muon anomalous magnetic moment in the chiral perturbation theory. © 2009 Elsevier B.V. All rights reserved.