Fermionic Dark Matter in a simple $t$-channel model

TL;DR

This paper investigates fermionic dark matter interacting via a simple t-channel model with scalar and vector mediators, analyzing constraints from relic density, direct detection, and collider searches, and highlighting differences between Dirac and Majorana DM.

Contribution

It provides a comprehensive analysis of fermionic dark matter in a minimal t-channel framework, including collider and direct detection constraints, with new insights into the viability of different mediator types.

Findings

Most parameter space for thermally produced Dirac DM is ruled out by direct detection.

Monojet searches impose strong bounds on Majorana DM, excluding masses below a few hundred GeV.

Collider constraints are less restrictive than direct detection for colored mediators.

Abstract

We consider a fermionic dark matter (DM) particle in renormalizable Standard Model (SM) gauge interactions in a simple $t$-channel model. The DM particle interactions with SM fermions is through the exchange of scalar and vector mediators which carry colour or lepton number. In the case of coloured mediators considered in this study, we find that if the DM is thermally produced and accounts for the observed relic density almost the entire parameter space is ruled out by the direct detection observations. The bounds from the monojet plus missing energy searches at the Large Hadron Collider are less stringent in this case. In contrast for the case of Majorana DM, we obtain strong bounds from the monojet searches which rule out DM particles of mass less than about a few hundred GeV for both the scalar and vector mediators.