The Search for Majorana Neutrinos

Speaker: Anupama Atre, University of Wisconsin Madison

When: November 27, 2006 (Mon), 12:30PM to 01:30PM (add to my calendar)

This event is part of the HET Seminar Series.

The Majorana nature of neutrinos can be experimentally verified only via lepton-number violating processes involving charged leptons. We study thirty lepton-number violating processes (LVP) mediated by Majorana neutrinos with masses in the eV range. In this extension of the SM stringent constraints on the rates of LVP were obtained by a combined analysis of neutrino oscillation and cosmology. Next, we study 36 LVP from the decays of a tau lepton and pseudo scalar mesons with contributions from heavy neutrinos. Unlike the light Majorana neutrino case, the rates of these processes would be enhanced due to the resonant contribution of Majorana neutrinos in the mass range ~ 100MeV to 10GeV. We calculate the transition rates and branching fractions and compare them to current bounds from direct experimental searches. The experimental non-observation of such LVP places stringent bounds on the mass and mixing of the Majorana neutrinos. We also extend the search to hadron collider experiments. We find that there could be significant sensitivity for resonant production of a Majorana neutrino in the mass range of 10–80GeV in the current run of the Tevatron with 2fb-1 integrated luminosity and in the mass range 10–400GeV at the LHC with 100fb-1.