Neutrino flavor transformations in supernovae as a probe for nonstandard neutrino-scalar interactions

TL;DR

This paper investigates how nonstandard neutrino-scalar interactions affect neutrino flavor transformations in supernovae, potentially revealing the nature of neutrinos and constraining new physics through supernova neutrino observations.

Contribution

It demonstrates that nonstandard neutrino self-interactions can significantly alter flavor oscillations, offering a new way to probe neutrino properties and interactions in supernova environments.

Findings

NSSI can dramatically change collective neutrino oscillations.

Flavor-preserving NSSI suppresses flavor transformation.

Flavor-violating NSSI promotes flavor transformation.

Abstract

We explore the possibility of probing the nonstandard interactions between the neutrino and a hypothetical massive scalar or pseudoscalar via neutrino flavor transformation in supernovae. We find that in the ultrarelativistic limit, the effective interaction between the neutrinos vanishes if neutrinos are Dirac fermions but not if they are Majorana fermions. The impact of the new neutrino interaction upon the flavor transformation above the neutrinosphere is calculated in the context of the multi-angle "neutrino bulb model". We find that the addition of the nonstandard neutrino self-interaction (NSSI) to the ordinary V-A self-interaction between neutrinos is capable of dramatically altering the collective oscillations when its strength is comparable to the standard, V-A, interaction. The effect of flavor-preserving (FP) NSSI is generally to suppress flavor transformation, while the flavor-violating (FV) interactions are found to promote flavor transformations. If the neutrino signal from a Galactic supernova can be sufficiently well understood, supernova neutrinos can provide complimentary constraints on scalar/pseudoscalar interactions of neutrinos as well as distinguishing whether the neutrino is a Majorana or Dirac fermion.