Dark Matter and Neutrino Masses from Global $U(1)_{B-L}$ Symmetry Breaking

TL;DR

This paper proposes a model linking neutrino masses and Dark Matter through a global $U(1)_{B-L}$ symmetry, utilizing a two-loop neutrino mass mechanism and stable fermionic Dark Matter candidates, avoiding constraints from $Z'$ searches.

Contribution

It introduces a novel global $U(1)_{B-L}$ symmetry-based framework connecting neutrino masses and Dark Matter, with a specific mechanism ensuring Dark Matter stability.

Findings

Dark Matter stability is guaranteed by a remnant $Z_2$ symmetry.

The model avoids severe constraints from $Z'$ searches unlike gauged $U(1)_{B-L}$ models.

Dark Matter phenomenology is consistent with current observations.

Abstract

We present a scenario where neutrino masses and Dark Matter are related due to a global $U(1)_{B-L}$ symmetry. Specifically we consider neutrino mass generation via the Zee--Babu two-loop mechanism, augmented by a scalar singlet whose VEV breaks the global $U(1)_{B-L}$ symmetry. In order to obtain a Dark Matter candidate we introduce two Standard Model singlet fermions. They form a Dirac particle and are stable because of a remnant $Z_2$ symmetry. Hence, in this model the stability of Dark Matter follows from the global $U(1)_{B-L}$ symmetry. We discuss the Dark Matter phenomenology of the model, and compare it to similar models based on gauged $U(1)_{B-L}$. We argue that in contrast to the gauged versions, the model based on the global symmetry does not suffer from severe constraints from $Z'$ searches.