# Search for Lepton Number and Flavor Violation in K+ and pi(0) Decays

Aliberti, R, Ambrosino, F, Ammendola, R, Angelucci, B, Antonelli, A, Anzivino, G, Arcidiacono, R, Bache, T, Baeva, A, Baigarashev, D
et al (show 192 more authors) (2021) Search for Lepton Number and Flavor Violation in K+ and pi(0) Decays. PHYSICAL REVIEW LETTERS, 127 (13). 131802-.

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## Abstract

Searches for the lepton number violating K^{+}→π^{-}μ^{+}e^{+} decay and the lepton flavor violating K^{+}→π^{+}μ^{-}e^{+} and π^{0}→μ^{-}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: B(K^{+}→π^{-}μ^{+}e^{+})<4.2×10^{-11}, B(K^{+}→π^{+}μ^{-}e^{+})<6.6×10^{-11} and B(π^{0}→μ^{-}e^{+})<3.2×10^{-10}. These results improve by 1 order of magnitude over previous results for these decay modes.

Item Type: Article NA62 Collaboration Faculty of Science and Engineering > School of Physical Sciences Symplectic Admin 17 Dec 2021 14:04 18 Jan 2023 21:18 10.1103/PhysRevLett.127.131802 https://journals.aps.org/prl/abstract/10.1103/Phys... https://livrepository.liverpool.ac.uk/id/eprint/3145578