Inverse seesaw in supersymmetry

TL;DR

This paper proposes a supersymmetric model where tiny neutrino masses are generated radiatively, with a mechanism that keeps the lightest neutrino massless at tree level and explains the smallness of neutrino masses.

Contribution

It introduces a novel inverse seesaw mechanism in supersymmetry that relies on radiative corrections and an approximate symmetry to generate tiny neutrino masses.

Findings

Neutrino masses arise from radiative contributions due to symmetry breaking.

Right-handed neutrino Majorana mass can be as low as keV scale.

The model naturally explains the smallness of neutrino masses.

Abstract

We study a mechanism where tiny neutrino masses arise only from radiative contribution in a supersymmetric model. In each generation, the tree-level light neutrino mass is rotated away by introducing a second SM singlet $s_{L}$ that forms a Dirac mass term with the right-handed neutrino $n_{R}$. Even with non-zero Majorana neutrino mass for the right-handed neutrinos $M_{R} \bar{n^{c}_{R}} n_{R}$, the lightest neutrino remains massless at tree level due to an approximate symmetry as $U(1)_{\nu-s}$. Holomorphic feature of superpotential ensures that the Majorana neutrino masses $M_{R} \bar{n^{c}_{R}} n_{R}$ and $M^{*}_{R} \bar{s^{c}_{L}} s_{L}$ are not generated simultaneously. However, the $U(1)_{\nu-s}$ is not respected by the SM gauge interactions or interaction with Higgs. Consequently, tiny neutrino masses arise from radiative contributions. It is also shown that the right-handed neutrino Majorana mass $M_{R}$ can be at $\cal O$(KeV) to obtain the proper light neutrino mass.