On lattice extraction of K --> pi pi amplitudes to O(p⁴) in Chiral Perturbation Theory

We show that lattice calculation of K --> pi pi and $epe$ amplitudes for (8,1) and (27,1) operators to O(p^4) in chiral perturbation theory is feasible when one uses K --> pi pi computations at the two unphysical kinematics allowed by the Maiani-Testa theorem, along with the usual (computable) two and three point functions, namely K --> 0, K --> pi (with momentum) and K - bar{K}. Explicit expressions for the finite logarithms emerging from our O(p^4) analysis to the above amplitudes are also given.