Dark matter interactions with muons in neutron stars

Abstract: Neutron stars contain a significant number of stable muons due to the large chemical potential and degenerate electrons. This makes them the unique vessel to capture muonphilic dark matter, which does not interact with other astrophysical objects, including Earth and its direct-detection experiments. The infalling dark matter can heat up the neutron star both kinetically and via annihilations, which is potentially observable with future infrared telescopes. New physics models for muonphilic dark matter can easily be motivated by, and connected to, existing anomalies in the muon sector, e.g., the anomalous magnetic moment or LHCb's recent hints for lepton-flavor non-universality in $B\to K\mu^+\mu^-$ decays. We study the implications for a model with dark matter charged under a local $U(1){L\mu-L_\tau}$.