On the search for 50 GeV neutrinos
  Using the computer code CompHEP we estimate the number of events and the background, at LEP II and TESLA, for the reaction $e^+ e^- \to N\bar{N}\gamma$, where $N$ is a hypothetical Dirac neutrino with mass of the order of 50 GeV. 
V.A. Ilyin, M. Maltoni, V.A. Novikov, L.B. Okun, A.N. Rozanov and M.I.   Vysotsky