High-precision determination of the $K_{e3}$ radiative corrections

TL;DR

This paper presents a high-precision calculation of electroweak radiative corrections in kaon decays, reducing theoretical uncertainties and indicating that Standard Model effects do not explain the $V_{us}$ anomaly.

Contribution

It introduces a novel chiral resummation technique and incorporates recent lattice QCD data to significantly lower the uncertainty in radiative correction calculations.

Findings

Uncertainty reduced from 10^{-3} to 10^{-4}.

Electroweak effects cannot explain the $V_{us}$ anomaly.

Results are consistent with chiral perturbation theory.

Abstract

We report a high-precision calculation of the Standard Model electroweak radiative corrections in the $K\to \pi e^+\nu(\gamma)$ decay as a part of the combined theory effort to understand the existing anomaly in the determinations of $V_{us}$. Our new analysis features a chiral resummation of the large infrared-singular terms in the radiative corrections and a well-under-control strong interaction uncertainty based on the most recent lattice QCD inputs. While being consistent with the current state-of-the-art results obtained from chiral perturbation theory, we reduce the existing theory uncertainty from $10^{-3}$ to $10^{-4}$. Our result suggests that the Standard Model electroweak effects cannot account for the $V_{us}$ anomaly.