Astrophysical limitations on possible tensor contributions to weak neutral-current interactions

Abstract

We consider the astrophysical implications of, and limits on, possible weak neutral-tensor-current interactions. Such interactions give the neutrino dipole moments that permit it to couple directly to photons. Photons in an astrophysical plasma, with $q^2\ne 0$, then decay into $\nu \overline{\nu }$ pairs. We discuss astrophysical limits, based on a comparison of stellar evolution theory and observations, that can be set on the strength of this modified plasma-neutrino energy-loss rate. We find that the best limit is probably set by a comparison of degenerate dwarf cooling times with observations of hot white dwarfs. We deduce that $\frac{G_T}{G_F}\lesssim \frac{1}{15}$, where $G_T$ is the coupling constant for neutral tensor currents and $G_F$ is the Fermi coupling constant.