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arXiv · 1905.07770

Searches for lepton number violating $K^+$ decays

NA62 collaboration
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Abstract

The NA62 experiment at CERN reports a search for the lepton number violating decays $K^+\to\pi^-e^+e^+$ and $K^+\to\pi^-\mu^+\mu^+$ using a data sample collected in 2017. No signals are observed, and upper limits on the branching fractions of these decays of $2.2\times 10^{-10}$ and $4.2\times 10^{-11}$ are obtained, respectively, at 90% confidence level. These upper limits improve on previously reported measurements by factors of 3 and 2, respectively.

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NA62 collaboration. 2019-05-19. Searches for lepton number violating $K^+$ decays. https://doi.org/10.1016/j.physletb.2019.07.041

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