Search for heavy neutral leptons in B-meson decays

Abstract

A search for long-lived heavy neutral leptons produced in B-meson decays and decaying to a $\hat{I}{¼}^{\pm }\ddot{I}{€}^{\mp }$ final state is performed with data collected by the LHCb experiment in proton-proton collisions at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of $5{\mathrm{fb}}^{-1}$. The results are interpreted in both lepton-number-conserving and lepton-number-violating scenarios. No significant excess is observed. Constraints are placed on the squared mixing element $|U_{\hat{I}¼N}{|}^2$ to the active muon neutrino, under the assumption that couplings to other lepton flavours are negligible, in the mass range of $1.6$-$5.5$ GeV.

All figures and tables, along with any supplementary material and additional information, are available at https://lbfence.cern.ch/alcm/public/analysis/full-details/1607/ (LHCb public pages)