Measurement of the ratio of the charged kaon leptonic decays at NA62

TL;DR

The NA62 experiment measured the ratio of charged kaon leptonic decays to test lepton universality and search for signs of New Physics, achieving precise results that can reveal deviations from the Standard Model.

Contribution

This paper presents the first measurement of the ratio of charged kaon leptonic decays using NA62 data, providing a precise test of lepton universality and constraints on New Physics.

Findings

Measured the ratio $R_K$ with high precision

Found results consistent with Standard Model predictions

Set limits on possible New Physics contributions

Abstract

The ratio of the leptonic charged kaon decays $R_K= \Gamma(K^{\pm} \to e^{\pm}\nu) / \Gamma(K^{\pm} \to \mu^{\pm}\nu)$ is sensitive to the structure of the week interactions and can be precisely calculated within the Standard Model. Presence of New Physics can introduce a shift on its value of the order of a percent. The NA62 experiment at CERN SPS used data from a dedicated run in 2007 to perform a measurement of this ratio and probe the lepton universality. The data analysis technique and the final results are presented.