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

Abstract

We propose a new theory framework to study the electroweak radiative corrections in Kl3 decays by combining the classic current algebra approach with the modern effective field theory. Under this framework, the most important mathcal{O} (GFα) radiative corrections are described by a single tensor Tμν 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 Vus in the future.