Search for K+ decays to a lepton and invisible particles



Lurkin, Nicolas, Akmete, A, Aliberti, R, Ambrosino, F, Ammendola, R, Angelucci, B, Antonelli, A, Anzivino, G, Arcidiacono, R, Bache, T
et al (show 216 more authors) (2022) Search for K+ decays to a lepton and invisible particles. In: The 22nd International Workshop on Neutrinos from Accelerators, 2021-9-6 - ?.

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Abstract

The NA62 experiment at CERN reports searches for K<sup>+</sup> → e<sup>+</sup>N, K<sup>+</sup> → µ<sup>+</sup>N and K<sup>+</sup> → µ<sup>+</sup>X decays, where N and X are massive invisible particles, using the 2016-2018 data set. The N particle is assumed to be a heavy neutral lepton, and the results are expressed as upper limits of O(10<sup>−9</sup>) and O(10<sup>−8</sup>) on the neutrino mixing parameter |U<inf>e4</inf>|<sup>2</sup> and |U<inf>µ4</inf>|<sup>2</sup>, improving on the earlier searches for heavy neutral lepton production and decays in the kinematically accessible mass range. The X particle is considered a scalar or vector hidden sector mediator decaying to an invisible final state, and upper limits of the decay branching fraction for X masses in the range 10-370 MeV/c<sup>2</sup> are reported for the first time, ranging from O(10<sup>−5</sup>) to O(10<sup>−7</sup>). An upper limit of 1.0 · 10<sup>−6</sup> is established at 90% CL on the K<sup>+</sup> → µ<sup>+</sup>ννν¯ branching fraction.

Item Type: Conference Item (Unspecified)
Divisions: Faculty of Science and Engineering > School of Physical Sciences
Depositing User: Symplectic Admin
Date Deposited: 14 Mar 2023 15:55
Last Modified: 05 Jun 2025 13:33
DOI: 10.22323/1.402.0157
Open Access URL: https://pos.sissa.it/402/157/
Related Websites:
URI: https://livrepository.liverpool.ac.uk/id/eprint/3169067