Axion-neutrino interactions in seesaw models and astrophysical probes

TL;DR

This paper investigates axion-neutrino interactions within seesaw models, assessing astrophysical constraints and potential effects on neutrino propagation, concluding that current bounds imply negligible observable impacts.

Contribution

It provides a detailed analysis of axion-neutrino couplings in seesaw models and evaluates their astrophysical and cosmological implications, highlighting the negligible effects under current constraints.

Findings

Axion-neutrino couplings are constrained by astrophysical limits.

Axion-mediated neutrino scattering effects are negligible with current bounds.

No observable signatures are expected from axion-neutrino interactions in current experiments.

Abstract

We study axion-neutrino interactions in neutrino-mass extensions of the Standard Model, focusing on the Type-I and inverse seesaw. In these frameworks the effective coupling $g_{a\nu}$ is tied to the axion scale and can be constrained using existing astrophysical limits on axion couplings to electrons. We then estimate the impact of axion-mediated scattering on neutrino propagation in two benchmarks: resonant interactions with the C$\nu$B and scattering on axion dark matter. In the parameter space allowed by current bounds, the resulting optical depths are extremely small, implying no observable signatures with present sensitivities.