# The $B-L$ Scotogenic Models for Dirac Neutrino Masses

## TL;DR

This paper develops one-loop and two-loop models within $U(1)_{B-L}$ extensions to generate Dirac neutrino masses, naturally forbidding Majorana terms and providing dark matter candidates stabilized by residual symmetries.

## Contribution

It introduces novel scotogenic models for Dirac neutrino masses with fixed fermion singlet numbers and exotic $B-L$ charges, incorporating residual discrete symmetries for dark matter stability.

## Key findings

- Models naturally forbid Majorana mass terms.
- Residual $Z_2$ or $Z_3$ symmetries stabilize dark matter.
- Phenomenological implications for lepton flavor violation, dark matter, leptogenesis, and collider signatures.

## Abstract

We construct the one-loop and two-loop scotogenic models for Dirac neutrino mass generation in the context of $U(1)_{B-L}$ extensions of standard model. It is indicated that the total number of intermediate fermion singlets is uniquely fixed by anomaly free condition and the new particles may have exotic $B-L$ charges so that the direct SM Yukawa mass term $\bar{\nu}_L\nu_R\overline{\phi^0}$ and the Majorana mass term $(m_N/2)\overline{\nu_R^C}\nu_R$ are naturally forbidden. After the spontaneous breaking of $U(1)_{B-L}$ symmetry, the discrete $Z_{2}$ or $Z_{3}$ symmetry appears as the residual symmetry and give rise to the stability of intermediated fields as DM candidate. Phenomenological aspects of lepton flavor violation, DM, leptogenesis and LHC signatures are discussed.