Generation-separated hypercharges and dark charges: origin of flavor, neutrino masses, and dark matter

Abstract

We study a framework with generation-separated hypercharges and dark charges. After the extended hypercharge symmetry $U(1)_{Y1}\otimes U(1)_{Y2}\otimes U(1)_{Y3}$ is spontaneously broken to the Standard Model $U(1)_Y$, hierarchical masses of charged fermions and small quark mixing can arise from higher-dimensional operators involving hyperon fields. Several realizations with different hyperon sectors are presented to illustrate possible flavor structures. Focusing on the realization with four hyperons, we examine neutrino mass generation through either a seesaw or a scotoseesaw mechanism, which can accommodate tiny neutrino masses and large neutrino mixing. The breaking of the dark gauge symmetry $U(1)_D$ leaves a residual $\mathbb{Z}_2$ symmetry that stabilizes dark matter, allowing either fermionic or scalar candidates with viable TeV-scale parameter regions consistent with the observed dark matter relic abundance and current direct detection constraints.