The Ademollo-Gatto theorem for lattice semileptonic decays

We present the results of the calculation of the Kℓ3 semileptonic form factor at zero momentum transfer, f+(0), obtained at one-loop in partially quenched chiral perturbation theory (with either nf=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[(MK2−Mπ2)3]. The formulae presented here can be useful for the mass extrapolation of the results obtained in lattice simulations to the physical point.