A Possible Solution to the Tritium Endpoint Problem
  Scalar or right-chiral interaction currents may be expected to produce a neutrino coupled to the electron which is different from, and perhaps even orthogonal to, that coupled to the electron by the standard model weak interaction. We show that, using reasonable parameter values for such additional interactions, it is possible to generate a spectrum which, if analyzed in the manner commonly employed by experimental groups, produces a negative neutrino mass-squared. 
G. J. Stephenson, Jr. (UNM) and T. Goldman (LANL)