Limits on the radiative decay of neutrinos

Abstract

Astronomical observations at the x-ray, optical, and radio frequencies are used to show that the lifetime of neutrinos for radiative decay divided by the rest mass, Τ₀/m_ν, exceeds 10¹⁷ sec/eV. If one makes the further assumption that m_ν>10^-3 eV, then Τ₀>~10¹⁹ sec. If there are other competing decays of neutrinos, it is then shown that Γ_νe(ν_e→x+γ)/Γ_νe(total)<~10^-15 and Γ_νμ(ν_μ→x+γ)/Γ_νμ(total)<~3×10^-6.