000001623 001__ 1623 000001623 005__ 20190815083034.0 000001623 037__ $$aBELLE2-TALK-CONF-2019-098 000001623 041__ $$aeng 000001623 088__ $$aBELLE2-TALK-DRAFT-2019-097 000001623 100__ $$aMinakshi Nayak 000001623 245__ $$aProposed search for a nu_tau-mixing heavy neutrino 000001623 260__ $$aAnomalies 2019$$c2019-07-18 000001623 300__ $$amult. p 000001623 520__ $$aAddition of right-handed neutrinos to the standard model can explain neutrino oscillations, dark matter, and the baryon asymmetry of the universe. The resulting mass-eigenstate "heavy neutral lepton” (HNL) may be produced at accelerators and may be long-lived, depending on the strength of its mixing with the standard-model neutrino. High-luminosity e+e- B factories produce large numbers of tau-lepton pairs, yielding the best sensitivity for an HNL that mixes primarily with the tau neutrino and has a mass below that of the tau lepton. I will report the first study of this type, showing how to use kinematic constraints to obtain the mass of the long-lived HNL despite the missing neutrino in the final state. Sensitivity projections for existing B factories and for Belle II will be shown. 000001623 8560_ $$fdoris.yangsoo.kim@desy.de 000001623 8564_ $$uhttps://docs.belle2.org/record/1623/files/BELLE2-TALK-CONF-2019-098.pdf