Search for <i>K</i><SUP>+</SUP> decays to a muon and invisible particles



Gil, E Cortina, Kleimenova, A, Minucci, E, Padolski, S, Petrov, P, Shaikhiev, A, Volpe, R, Numao, T, Petrov, Y, Velghe, B
et al (show 192 more authors) (2021) Search for <i>K</i><SUP>+</SUP> decays to a muon and invisible particles. PHYSICS LETTERS B, 816. p. 136259.

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Abstract

The NA62 experiment at CERN reports searches for K+→μ+N and K+→μ+νX 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(10−8) of the neutrino mixing parameter |Uμ4|2 for N masses in the range 200–384 MeV/c2 and lifetime exceeding 50 ns. 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/c2 are reported for the first time, ranging from O(10−5) to O(10−7). An improved upper limit of 1.0×10−6 is established at 90% CL on the K+→μ+ννν¯ branching fraction.

Item Type: Article
Divisions: Faculty of Science and Engineering > School of Physical Sciences
Depositing User: Symplectic Admin
Date Deposited: 10 May 2021 10:27
Last Modified: 16 Oct 2023 16:26
DOI: 10.1016/j.physletb.2021.136259
Related URLs:
URI: https://livrepository.liverpool.ac.uk/id/eprint/3121648