# Hiding Thermal Dark Matter with Leptons

## TL;DR

This paper investigates leptophilic Majorana dark matter models that attempt to evade current experimental constraints, finding that most are excluded below 100 GeV, but heavier masses remain potentially detectable through indirect detection.

## Contribution

It introduces a class of leptophilic Majorana dark matter models and analyzes their viability considering electroweak symmetry breaking and experimental constraints.

## Key findings

- Models below 100 GeV are excluded by current data.
- Heavier dark matter remains viable and detectable via indirect signals.
- Couplings to quarks are generically induced, constraining these models.

## Abstract

Any form of dark matter which was in thermal equilibrium with the Standard Model in the early Universe must have some annihilation mechanism in order to avoid overclosure. In general, such models are now constrained by the negative experimental results from colliders, direct detection, and indirect detection, all of which are capable of probing interactions at the approximate strength suggested by a thermal cross section. It is timely to consider what scenarios of thermal dark matter which are still viable. In this paper we consider a class of dark matter models which is designed to avoid many of the current constraints: Majorana dark matter coupling to the Standard Model through leptophilic singlet scalars and pseudoscalars. We show that requiring realistic electroweak symmetry breaking generically forces the mediators to couple with quarks, allowing these models to be constrained by the current experimental data. We find that -- barring fine-tuning -- this type of thermal dark matter is excluded by a combination of direct and indirect detection for masses below $\sim 100$ GeV. Heavier dark matter is still viable, but in principle visible via its indirect detection signature.