Abstract

We study the rare decays of charged ? mesons, ? + ? e +e +? -??? and ? + ? e +? -e +? e induced by a sterile neutrino N with a mass in the range m ? < m N < m ?. The first process violates Lepton Number by two units and so occurs only if N is Majorana, while the second process conserves Lepton Number and occurs irrespective of the Majorana or Dirac character of N. We study a way to distinguish the Majorana vs. Dirac character of N in these processes using the muon spectrum. We also find that the branching ratios could be at the reach of high luminosity experiments like Project X at FNAL or any proposed neutrino (or muon) factories worldwide. © 2012 SISSA.