Comprehensive exploration of t-channel simplified models of dark matter

TL;DR

This paper thoroughly investigates six classes of t-channel simplified dark matter models with a coloured mediator, analyzing their parameter constraints from cosmological, astrophysical, and collider data, revealing strong bounds especially for self-conjugate dark matter.

Contribution

It provides a comprehensive analysis of six t-channel dark matter models, highlighting the constraints from various searches and the importance of same-sign mediator pair production.

Findings

Complex dark matter is excluded by cosmology and astrophysics.

Mediator and dark matter masses are constrained to the TeV scale.

Same-sign mediator pair production is a key process in setting bounds.

Abstract

We analyse six classes of t-channel dark matter simplified models in which the Standard Model field content is extended by a coloured mediator and a dark matter state. The two new states are enforced to be odd under a new parity, while all Standard Model fields are taken even so that dark matter stability is guaranteed. We study several possibilities for the spin of the new particles and the self-conjugate property of the dark matter, and we focus on model configurations in which the dark matter couples to the right-handed up quark for simplicity. We investigate how the parameter spaces of the six models can be constrained by current and future cosmological, astrophysical and collider searches, and we highlight the strong complementary between those probes. Our results demonstrate that scenarios featuring a complex (non self-conjugate) dark matter field are excluded by cosmology and astrophysics alone, the only possibility to avoid these bounds being to invoke very weak couplings and mechanisms such as conversion-driven freeze-out. For models with self-conjugate dark matter, mediator and dark matter masses are pushed deep into the TeV regime, with the lower limits on the mediator mass reaching 3 to 4 TeV and those on the dark matter mass 1 to 2 TeV. In large parts of the parameter space these strong bounds are driven by same-sign mediator pair production, a channel so far not considered in the experimental analyses embedding t-channel dark matter model interpretations.