# Search for heavy neutral lepton production in K+ decays to positrons

Cortina Gil, E, Kleimenova, A, Minucci, E, Padolski, S, Petrov, P, Shaikhiev, A, Volpe, R, Numao, T, Petrov, Y, Velghe, B
et al (show 192 more authors) (2020) Search for heavy neutral lepton production in K+ decays to positrons. Physics Letters B, 807. p. 135599.

 Text Heavy.pdf - Published version Download (564kB) | Preview

## Abstract

A search for heavy neutral lepton (N) production in K+→e+N decays using the data sample collected by the NA62 experiment at CERN in 2017–2018 is reported. Upper limits of the extended neutrino mixing matrix element |Ue4|2 are established at the level of 10−9 over most of the accessible heavy neutral lepton mass range 144–462 MeV/c2, with the assumption that the lifetime exceeds 50 ns. These limits improve significantly upon those of previous production and decay searches. The |Ue4|2 range favoured by Big Bang Nucleosynthesis is excluded up to a mass of about 340 MeV/c2.

Item Type: Article Symplectic Admin 17 Jul 2020 07:57 18 Jan 2023 23:40 10.1016/j.physletb.2020.135599 https://livrepository.liverpool.ac.uk/id/eprint/3094255