Plasma induced neutrino spin-flip in a supernova and new bounds on the neutrino magnetic moment

TL;DR

This paper refines the calculation of neutrino spin-flip processes in supernova cores, incorporating plasma polarization effects, and establishes new, more stringent upper bounds on the neutrino magnetic moment based on supernova observations.

Contribution

It provides a more complete plasma polarization model for neutrino spin-flip in supernovae and derives tighter bounds on the neutrino magnetic moment from observational data.

Findings

New upper bounds on neutrino magnetic moment: (0.4-1.1) x 10^{-12} μ_B.

Plasma polarization effects, especially proton contributions, are crucial.

Improved bounds from SN1987A data are 3 to 7 times more restrictive.

Abstract

The neutrino chirality-flip process under the conditions of the supernova core is investigated in detail with the plasma polarization effects in the photon propagator taken into account in a more complete form than in earlier publications. It is shown in part that the contribution of the proton fraction of plasma is essential. New upper bounds on the neutrino magnetic moment are obtained: mu_nu < (0.5 - 1.1) 10^{-12} mu_B from the limit on the supernova core luminosity for nu_R emission, and mu_nu < (0.4 - 0.6) 10^{-12} mu_B from the limit on the averaged time of the left-handed neutrino washing out. The best upper bound on the neutrino magnetic moment from SN1987A is improved by the factor of 3 to 7.