Enhanced neutrino polarizability

TL;DR

This paper investigates how light scalar or pseudoscalar mediators can significantly enhance neutrino-photon interactions, leading to measurable neutrino polarizability and exploring the resulting phenomenology and model implications.

Contribution

It introduces models with light mediators that enhance neutrino polarizability, overcoming suppression from neutrino masses, and details the phenomenological constraints and explicit model constructions.

Findings

Enhanced neutrino polarizability via light mediators is feasible.

Constraints on mediator couplings are thoroughly analyzed.

Explicit models modify the inverse see-saw majoron to achieve enhancement.

Abstract

We point out that neutrinos can have enhanced couplings to photons, if light (pseudo)scalar mediators are present, resulting in potentially measurable neutrino polarizability. We show that the expected suppression from small neutrino masses can be compensated by the light mediator mass, generating dimension 7 Rayleigh operators at low scales. We explore the rich phenomenology of such models, computing in details the constraints on the viable parameter space, spanned by the couplings of the mediator to neutrinos and photons. Finally, we build several explicit models that lead to enhanced neutrino polarizability by modifying the inverse see-saw majoron, i.e., the pseudo-Nambu-Goldstone boson of the $U(1)_L$ global lepton number responsible for generating small neutrino masses.