$U(1)_{Y'}$ universal seesaw

TL;DR

This paper proposes an extension of the Standard Model with an additional $U(1)_{Y'}$ gauge symmetry, introducing new particles and operators to generate fermion masses and explain baryon asymmetry via Dirac leptogenesis.

Contribution

It introduces a novel $U(1)_{Y'}$ extension with a unified seesaw mechanism and multiple realizations, linking neutrino mass generation with baryogenesis.

Findings

Successful Dirac leptogenesis achieved

Fermion masses generated via dimension-5 operators

Anomaly cancellation with three right-handed neutrinos

Abstract

We extend the $SU(3)_c \times SU(2)_L \times U(1)_Y$ standard model by a $U(1)_{Y'}$ gauge symmetry. Three right-handed neutrinos are introduced to cancel the gauge anomaly. One Higgs singlet is responsible for spontaneously breaking the $U(1)_{Y'}$ symmetry while the standard model Higgs doublet does not carry any $U(1)_{Y'}$ charges. The down-type quarks, up-type quarks, charged leptons and neutral neutrinos obtain their Dirac masses through four types of dimension-5 operators constructed by the fermion doublets and singlets with the Higgs doublet and singlet. This effective theory is realized in three renormalizable contexts with heavy fermion singlets, scalar doublets and fermion doublets. The heavy fermion singlets and doublets for generating the neutrino masses also accommodate a successful Dirac leptogenesis to explain the baryon asymmetry in the universe.