Neutrino spin-flavour precession in magnetized white dwarf

TL;DR

This paper explores how magnetized white dwarfs can be used to study neutrino spin-flavour precession, potentially distinguishing between Dirac and Majorana neutrinos through their different transition probabilities.

Contribution

It proposes white dwarf systems as a new environment for investigating neutrino spin-flavour oscillations and their implications for neutrino nature.

Findings

Dirac neutrinos have higher spin-flavour transition probabilities than Majorana neutrinos.

Magnetized white dwarfs can enhance neutrino cooling and oscillation effects.

Transition probabilities are sensitive to the neutrino magnetic moment.

Abstract

Due to notoriously small value of the neutrino magnetic moment, the phenomena of neutrino spin flavour precession (SFP) requires very high magnetic field. This makes only a handful of systems suitable to study this phenomena. By the observation of SFP, the Dirac and Majorana nature of neutrinos is expected to be distinguished. In this work, we point out the potential of white dwarf (WD) system in studying the spin-flavour oscillation of neutrinos. From recent analysis, it has been found that young isolated WDs may harbor very strong internal magnetic field, even without exhibiting any surface magnetic field. The presence of magnetic field enhances the cooling process and along with that, renders the spin-flavour oscillation of neutrinos emitted in the neutrino cooling process. Employing the standard WD specifications, we analyse whether a magnetized WD is a suitable environment to distinguish between the Dirac and Majorana nature of neutrino. Lower value of spin flavour transition probability implies reduced active neutrino flux which is possible to be estimated in terrestrial neutrino detectors. We find that the spin flavour transition probability of Dirac neutrinos is much higher in comparison to the Majorana neutrino which converts the active neutrino flavours to sterile in a significant amount. We also examine the sensitivity of the spin flavour transition probability to the neutrino magnetic moment.