Lepton universality tests with leptonic kaon decays

TL;DR

This paper reports on the measurement of the ratio of leptonic kaon decay rates, $R_K$, using data from the NA62 experiment, providing tests of lepton flavor universality and the Standard Model.

Contribution

The paper presents a preliminary measurement of $R_K$ based on 59963 $K^+ ightarrow e u_e$ candidates, contributing to tests of lepton universality.

Findings

Preliminary $R_K$ value consistent with Standard Model predictions.

Large dataset of kaon decays collected in 2007.

Supports lepton flavor universality within experimental uncertainties.

Abstract

The NA62 experiment at CERN aims to use rare kaon decays to search for new phenomena beyond the Standard Model. During the current short term phase (data taking completed in years 2007-8), the ratio $R_K = \Gamma(K^+ \rightarrow e \nu_e (\gamma)) / \Gamma(K^+ \rightarrow \mu \nu_{\mu} (\gamma))$ of leptonic decay rates is studied, which tests the structure of weak interactions and lepton flavour universality. In this paper, the $R_K$ analysis is summarized, and the preliminary result is discussed, based on 59963 $K^+ \rightarrow e \nu_e $ candidates collected in 2007.