Restrictions on the mixing of electron and heavy neutrinos from superallowed 0 +→0 + fermi β-decays

Abstract

The consistency of the vector coupling constant extracted from the superallowed 0 +→0 + nuclear β-decays with different maximal energies allows one to obtain a new limit on the mixing of the electron and heavy neutrinos: sin 2 θ Vh≲10 −2 for the mass range 0.5–5 MeV of v h where a limit of only ≲10 −1 previously existed.