Anomaly-free Abelian gauge symmetries with Dirac seesaws

Abstract

We perform a systematic analysis of Standard Model extensions with an additional anomaly-free gauge $U(1)$ symmetry, to generate tree-level Dirac neutrino masses. An anomaly-free symmetry demands nontrivial conditions on the charges of the unavoidable new states. An intensive scan was performed, looking for solutions generating neutrino masses by the type-I and type-II tree-level Dirac seesaw mechanism, via operators with dimension 5 and 6, that correspond to active or dark symmetries. Special attention was paid to the cases featuring no extra massless chiral fermions or multicomponent dark matter with unconditional stability.

Comments: 13+3 pages, 2 figures. V2: Typos corrected. Matches version accepted for publication in EPJC. arXiv admin note: substantial text overlap with arXiv:2102.06211