Electromagnetic corrections to K -\u3epi pi. II. Dispersive matching

Abstract

We express the leading electromagnetic corrections in K → ππ as integrals over the virtual photon squared-momentum Q2. The high Q2 behavior is obtained via the operator product expansion. The low Q2 behavior is calculated using chiral perturbation theory. We model the intermediate Q2 region using resonance contributions in order to enforce the matching of these two regimes. Our results confirm our previous estimates that the electromagnetic corrections provide a reasonably small shift in the I = 3/2 amplitude

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