Testing mu-e universality with Kl2 decays

TL;DR

This paper reports on a high-precision measurement of the ratio R_K in kaon decays, which tests the universality of mu-e interactions and searches for signs of new physics beyond the Standard Model.

Contribution

It provides a more precise measurement of R_K than previous results, enhancing the sensitivity to potential new physics effects in weak interactions.

Findings

Preliminary R_K measurement is twice as precise as the world average.

Current data collection aims for sub-percent precision in R_K.

Results are consistent with Standard Model predictions.

Abstract

The ratio R_K=Gamma(Ke2)/Gamma(Kmu2) provides a very powerful probe for the weak interactions structure. This ratio of decay rates is calculated with very high precision within the Standard Model but the corrections due to the presence of New Physics could be as high as 3%. The data obtained by the NA48 experiment at the CERN SPS accelerator during a 56 hours special run in 2004 has been analyzed.The precision of the preliminary result for R_K is two times better than the world average but is still insufficient to probe the existence of physics Beyond the Standard Model. Currently the experiment is taking data dedicated to the sub-percent precision measurement of R_K.