Search for Lepton Number and Flavor Violation in K + and π 0 Decays

Le résumé fourni par la source

Searches for the lepton number violating ${K}^{+}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\mu}}^{+}{e}^{+}$ decay and the lepton flavor violating ${K}^{+}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}{e}^{+}$ and ${\ensuremath{\pi}}^{0}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{\ensuremath{-}}{e}^{+}$ decays are reported using data collected by the NA62 experiment at CERN in 2017--2018. No evidence for these decays is found and upper limits of the branching ratios are obtained at 90% confidence level: $\mathcal{B}({K}^{+}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\mu}}^{+}{e}^{+})<4.2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}11}$, $\mathcal{B}({K}^{+}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}{e}^{+})<6.6\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}11}$ and $\mathcal{B}({\ensuremath{\pi}}^{0}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{\ensuremath{-}}{e}^{+})<3.2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}10}$. These results improve by 1 order of magnitude over previous results for these decay modes.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.