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 ${q}^{2}\ensuremath{\ne}0$, then decay into $\ensuremath{\nu}\overline{\ensuremath{\nu}}$ 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 $\frac{{G}_{T}}{{G}_{F}}\ensuremath{\lesssim}\frac{1}{15}$, where ${G}_{T}$ is the coupling constant for neutral tensor currents and ${G}_{F}$ is the Fermi coupling constant.