Neutrino-antineutrino oscillations induced by strong magnetic fields in dense matter

TL;DR

This paper investigates how strong magnetic fields in dense matter can induce neutrino-antineutrino oscillations, leading to flavor equilibrium, with implications for supernovae and magnetar environments.

Contribution

It introduces a simulation-based analysis of neutrino-antineutrino oscillations in dense matter under strong magnetic fields, proposing conditions for flavor equilibration.

Findings

Flavor equilibration depends on baryon density and electron fraction.

Oscillations are suppressed in neutron-rich, high-density matter.

Magnetic fields >10^{14} G can enable flavor equilibration near proto-neutron stars.

Abstract

We simulate neutrino-antineutrino oscillations caused by strong magnetic fields in dense matter. With the strong magnetic fields and large neutrino magnetic moments, Majorana neutrinos can reach flavor equilibrium. We find that the flavor equilibration of neutrino-antineutrino oscillations is sensitive to the values of the baryon density and the electron fraction inside the matter. The neutrino-antineutrino oscillations are suppressed in the case of the large baryon density in neutron (proton)-rich matter. On the other hand, the flavor equilibration occurs when the electron fraction is close to $0.5$ even in the large baryon density. From the simulations, we propose a necessary condition for the equilibration of neutrino-antineutrino oscillations in dense matter. We also study whether such necessary condition is satisfied near the proto-neutron star by using results of neutrino hydrodynamic simulations of core-collapse supernovae. In our explosion model, the flavor equilibration would be possible if the magnetic field on the surface of the proto-neutron star is larger than $10^{14}$ G which is the typical value of the magnetic fields of magnetars.