# Capture of Leptophilic Dark Matter in Neutron Stars

## TL;DR

This paper investigates how neutron stars can capture leptophilic dark matter through scattering with electrons and muons, leading to observable heating that surpasses current detection limits.

## Contribution

It provides a detailed analysis of leptophilic dark matter capture in neutron stars, including loop-induced couplings to quarks and the potential for strong observational constraints.

## Key findings

- Neutron stars can set very strong limits on dark matter-lepton interactions.
- Muon scattering provides the greatest sensitivity among leptons.
- Projected sensitivity exceeds current terrestrial direct detection bounds.

## Abstract

Dark matter particles will be captured in neutron stars if they undergo scattering interactions with nucleons or leptons. These collisions transfer the dark matter kinetic energy to the star, resulting in appreciable heating that is potentially observable by forthcoming infrared telescopes. While previous work considered scattering only on nucleons, neutron stars contain small abundances of other particle species, including electrons and muons. We perform a detailed analysis of the neutron star kinetic heating constraints on leptophilic dark matter. We also estimate the size of loop induced couplings to quarks, arising from the exchange of photons and Z bosons. Despite having relatively small lepton abundances, we find that an observation of an old, cold, neutron star would provide very strong limits on dark matter interactions with leptons, with the greatest reach arising from scattering off muons. The projected sensitivity is orders of magnitude more powerful than current dark matter-electron scattering bounds from terrestrial direct detection experiments.