# A feeble window on leptophilic dark matter

## TL;DR

This paper investigates a leptophilic dark matter model with feeble interactions and a compressed mass spectrum, analyzing relic abundance and long-lived particle signatures at colliders.

## Contribution

It introduces a simplified leptophilic dark matter model with a Majorana fermion and charged scalar, exploring relic abundance mechanisms and collider signatures of long-lived particles.

## Key findings

- Relic abundance varies from freeze-in to freeze-out depending on Yukawa coupling.
- Long-lived charged scalars produce distinctive collider signatures.
- Experimental searches can probe significant parts of the parameter space.

## Abstract

In this paper we study a leptophilic dark matter scenario involving feeble dark matter coupling to the Standard Model (SM) and compressed dark matter-mediator mass spectrum. We consider a simplified model where the SM is extended with one Majorana fermion, the dark matter, and one charged scalar, the mediator, coupling to the SM leptons through a Yukawa interaction. We first discuss the dependence of the dark matter relic abundance on the Yukawa coupling going continuously from freeze-in to freeze-out with an intermediate stage of conversion driven freeze-out. Focusing on the latter, we then exploit the macroscopic decay length of the charged scalar to study the resulting long-lived-particle signatures at collider and to explore the experimental reach on the viable portion of the parameter space.