Improved upper limits of generation-mixing amplitudes /b U//sub ie/ are presented for the electron-flavour in the heavy neutrino mass range of 20-70 MeV//b c//sup 2/. In conjunction with astrophysical considerations the new limits tend to exclude together the existence of heavy neutrinos in the investigated mass range.
De Leener-Rosier, N. ; Deutsch, Jules ; Lebrun, Marcel ; Naviliat-Cuncic, O. ; Prieels, René ; et. al. New limits on generation mixing for massive neutrinos from pi rarr e nu decay. In: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics, Vol. 177, no. 2, p. 228-232 (1986)
