Search for a Sterile Neutrino in τ Decays at B-factories

  Minakshi Nayak  ,  Abner Soffer  
Tel Aviv University

We propose a new method to search for a sterile neutrino that mixes predominantly with a τ-neutrino and is lighter than the τ-lepton. The method uses the large e+e- → τ+τ- samples collected at B-factory experiments to produce the sterile neutrino in τ-lepton decays.  The sensitivity of the method is up to 10 times tighter than the current limit when using current B-factory data, and by 2 orders of magnitude with the full Belle II data sample. In addition, this method enables measurement of the sterile neutrino mass despite the presence of an undetectable neutrino.