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

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 q2≠0, then decay into νν¯ 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 GTGF≲115, where GT is the coupling constant for neutral tensor currents and GF is the Fermi coupling constant.