Physical implications of a double right-handed gauge symmetry

TL;DR

This paper proposes a novel extension of the Standard Model with a double right-handed $U(1)$ gauge symmetry, explaining fermion mass hierarchies, neutrino masses, and dark matter stability, with testable collider signatures.

Contribution

It introduces a new gauge symmetry framework that naturally accounts for fermion mass hierarchies, neutrino masses, and dark matter stability, with detailed phenomenological implications.

Findings

Reproduces observed fermion mass hierarchy through radiative mechanisms.

Generates neutrino mass differences consistent with experimental data.

Identifies collider signatures for new gauge bosons at LHC and future colliders.

Abstract

Guided by the flipping principle, we propose a novel extension of the Standard Model based on a double right-handed $U(1)$ gauge symmetry. In this framework, all left-handed fermions are neutral, while right-handed fermions of the third generation carry charges distinct from those of the first two generations. This structure naturally explains the observed Standard Model fermion mass hierarchy: the heavy masses of the third generation are generated at tree level, while the lighter masses of the first and second generations arise radiatively at the one-loop level. For the active neutrino sector, the tiny masses are generated through a combination of tree-level and two-loop seesaw mechanisms. Crucially, this approach successfully reproduces the observed neutrino mass hierarchy, with the atmospheric mass-squared difference generated at tree level and the solar neutrino mass squared difference emerging at the two-loop level. These hierarchical patterns stem from the interplay between gauge invariance and a residual parity symmetry that survives the spontaneous breaking of the extended gauge group. The same residual symmetry stabilizes a viable scalar singlet dark matter candidate, which we show can reproduce the observed relic abundance while remaining consistent with current direct detection bounds. After addressing constraints from electroweak precision tests and flavor-changing neutral currents, we explore the discovery prospects for the new neutral bosons at existing and future colliders, including the LEP, LHC, and a future ILC.