Dark matter and Collider signals in supersymmetric $U(1)^\prime$ models with non-universal $Z^\prime$ couplings

TL;DR

This paper explores supersymmetric models with an extra U(1) gauge symmetry featuring family-dependent couplings, which relax collider constraints and allow the singlino to be a dark matter candidate, with potential signals at the LHC.

Contribution

It introduces a simple family-dependent U(1)′ charge assignment that weakens Z′ mass constraints and analyzes dark matter and collider signals in these models.

Findings

Z′ decays into di-taus but not di-leptons, relaxing mass constraints.

Singlino can be the dark matter candidate with lowered mass.

Potential LHC signals from Z′ decays into charginos and neutralinos.

Abstract

We analyse supersymmetric models augmented by an extra $U(1)$ gauge group. To avoid anomalies in these models without introducing exotics, we allow for family-dependent $U(1)^\prime$ charges, and choose a simple form for these, dependent on one $U(1)^\prime$ charge parameter only. With this choice, $Z^\prime$ decays into di-taus but not di-leptons, weakening considerably the constraints on its mass. In the supersymmetric sector, the effect is to lower the singlino mass, allowing it to be the dark matter candidate. We investigate the dark matter constraints and collider implications of such models, with mostly singlino, or mostly higgsinos, or a mixture of the two as lightest supersymmetric particles. In these scenarios, $Z^\prime$ decays significantly into chargino or neutralino pairs, and thus indirectly into final state leptons. We devise benchmarks which, with adequate cuts, can yield signals visible at the high-luminosity LHC.