Singlet-Doublet Fermionic Dark Matter in Gauge Theory of Baryons

TL;DR

This paper proposes a minimal gauge extension of the Standard Model with a baryon number symmetry, introducing exotic fermions to cancel anomalies, and explores a two-component fermionic dark matter model that is consistent with current experimental constraints.

Contribution

It introduces an anomaly-free $U(1)_B$ gauge extension with exotic fermions and a two-component fermionic dark matter scenario that relaxes direct detection constraints.

Findings

Viable dark matter parameter space identified.

Model can be tested via direct, indirect, collider, and gravitational wave experiments.

Anomaly cancellation achieved with three exotic fermions.

Abstract

We are considering a minimal $U(1)_B$ extension of the Standard Model (SM) by promoting the baryon number as a local gauge symmetry to accommodate a stable dark matter (DM) candidate. The gauge theory of baryons induces non-trivial triangle gauge anomalies, and we provide a simple anomaly-free solution by adding three exotic fermions. A scalar $S$ spontaneously breaks the $U(1)_B$ symmetry, leaving behind a discrete $Z_2$ symmetry that ensures the stability of the lightest exotic fermion was originally introduced to cancel the triangle gauge anomalies. Scenarios with weakly interacting DM candidates having non-zero hypercharge usually face stringent constraints from experimental bounds on the DM spin-independent direct-detection (SIDD) cross-section. In this work, we consider a two-component singlet-doublet fermionic dark matter scenario, which significantly relaxes the constraints from bounds on the DM SIDD cross-section for suppressed singlet-doublet mixing. We show that the model offers a viable parameter space for a cosmologically consistent DM candidate that can be probed through direct and indirect searches, collider experiments, and gravitational wave (GW) experiments.