Axial-vector form factors for Kl2γ and πl2γat O(p6) in chiral perturbation theory

We present two-loop calculations on the axial-vector form factors F-A of semileptonic radiative kaon and pion decays in chiral perturbation theory. The relevant dimension-6 terms of the Lagrangian are evaluated from the resonance contribntion and the results of the irreducible two-loop graphs, of the sunset topology are given in detail. We also explicitly show that the divergent parts in F-A are cancelled exactly as required. (C) 2004 Elsevier B.V. All rights reserved.