A new theory framework for the electroweak radiative corrections in Kl3 decays

We propose a new theory framework to study the electroweak radiative corrections in K-l3 decays by combining the classic current algebra approach with the modern effective field theory. Under this framework, the most important O(G(F)alpha) radiative corrections are described by a single tensor T-mu nu involving the time-ordered product between the charged weak current and the electromagnetic current, and all remaining pieces are calculable order-by-order in Chiral Perturbation Theory. We further point out a special advantage in the K-l3(0) channel that it suffers the least impact from the poorly-constrained low-energy constants. This finding may serve as a basis for a more precise extraction of the matrix element V-us in the future.