Majorana Neutrinos and -Decay

Abstract

The µ-decay is analyzed as a tool to determine whether neutrinos are Majorana or Dirac particles, within the framework of the effective weak interaction Hamiltonian with the (V±A) currents. If the CP-violating term n_µ·(p_e×n_e) is detected where n stands for the polarization vector, this observation indicates the following facts; the Majorana property of neutrino, the existence of the right-handed current, the non-zero mixing between electron- and muon-neutrinos and the non-zero CP-violating phases in the leptonic sector. Various characters of quantities such as energy spectrum and (p_e×n_µ)·(p_e×n_e) for Majorana neutrinos are compared with those for Dirac neutrinos. It is argued that the complex phases intrinsic to the Majorana neutrino system are really the CP-violating phases.