The Ademollo-Gatto theorem for lattice semileptonic decays

We present the results of the calculation of the K-l3 semileptonic form factor at zero momentum transfer, f(+)(0), obtained at one-loop in partially quenched chiral perturbation theory (with either n(f) = 2, or nf = 3, and with generic valence and sea quark masses). We show that for nf = 2, and at the one-loop level, when the masses of the valence and sea light quarks are equal, the correction is of O[(M-K(2) - M-pi(2))(3)]. The formulae presented here can be useful for the mass extrapolation of the results obtained in lattice simulations to the physical point. (c) 2005 Elsevier B.V. All rights reserved.