Search for Heavy Neutral Leptons in T2K Experiment

The paper reports on search for heavy neutrinos $$(N)$$ decays with masses mN < 493 1pt \,MeV/c² . Heavy neutrinos can be produced in decays: K±,π ± → l±N , where (l = e,μ ) . Considered heavy neutrino decay modes are the following: N → lα±π ∓, N → lα⁺lβ⁻ν (ν ̄) , where (α ,β = e,μ ) . Search for signal events is performed in Time Projection Chambers (TPCs) of ND280 detector of T2K experiment. Inclusion of more statistics, a new tracking method in TPCs and an updated Monte Carlo model aid in an increase of the sensitivity of the earlier analysis of 2019 and additionally helps to extend the studies into the lower mass region. Preliminary signal selection efficiencies, statistical and systematic uncertainties, expected number of background events and expected experiment sensitivity are presented.