Improved Constraints on Sterile Neutrinos in the MeV to GeV Mass Range

Abstract

Improved upper bounds are presented on the coupling $|U_{e4}{|}^2$ of an electron to a sterile neutrino ${\nu }_4$ from analyses of data on nuclear and particle decays, including superallowed nuclear beta decays, the ratios $R_{e/\mu }^{(\pi )}=BR({\pi }^{+}\to e^{+}{\nu }_e)/BR({\pi }^{+}\to {\mu }^{+}{\nu }_{\mu })$, $R_{e/\mu }^{(K)}$, $R_{e/\tau }^{(D_s)}$, and $B_{e2}^{+}$ decay, covering the mass range from MeV to GeV.

Comments: 6 pages, latex, 1 eps file