Comment on Recent Argument That Neutrinos Are Not Majorana Particles

Existing data on neutrino-electron scattering do not imply that neutrinos are not Majorana particles. The question of whether neutrinos are of Majorana or of Dirac character remains completely open. Recently, it has been argued that existing data imply that neutrinos are not Majorana particles. The argument is as follows: 1. If some neutrino is a Majorana particle, then its vector neutral current (NC) vanishes. 2. The CHARM II experiment has found that, at least at the 2σ level, the product of the vector NC couplings of a νμ and an electron is nonzero. 2 3. If, as suggested by the CHARM II experiment, the νμ vector NC coupling is really nonzero, then the νμ cannot be a Majorana neutrino. In that case, the other neutrinos are probably not Majorana particles either. This argument is not correct. In particular, the assertion in step (2) is not right. The CHARM II experiment studied the NC reactions (—) νμ e→ (—) νμ e. As explained below, experiments on NC interactions between a νμ (and ν̄μ) and some target cannot determine the νμ NC vector coupling. ∗National Science Foundation preprint NSF-PT-97-1. The statements in this paper are not official views of the National Science Foundation.