Electromagnetic corrections to K ->pi pi. II. Dispersive matching

We express the leading electromagnetic corrections in $\stackrel{\ensuremath{\rightarrow}}{K}\ensuremath{\pi}\ensuremath{\pi}$ as integrals over the virtual photon squared momentum ${Q}^{2}.$ The high ${Q}^{2}$ behavior is obtained via the operator product expansion. The low ${Q}^{2}$ behavior is calculated using chiral perturbation theory. We model the intermediate ${Q}^{2}$ 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 $\ensuremath{\Delta}I=3/2$ amplitude.