Probing dark matter with disappearing tracks at the LHC

Models where dark matter is a part of an electroweak multiplet feature charged particles with macroscopic lifetimes due to the charged-neutral mass split of the order of pion mass. At the Large Hadron Collider, the ATLAS and CMS experiments will identify these charged particles as disappearing tracks, since they decay into a massive invisible dark matter candidate and a very soft charged Standard-Model particle, which fails to pass the reconstruction requirements. While ATLAS and CMS have focused on the supersymmetric versions of these scenarios, we have performed here the reinterpretation of the latest ATLAS disappearing track search for a suite of dark matter multiplets with different spins and electroweak quantum numbers. More concretely, we consider the cases of the inert two Higgs doublet, minimal fermion dark matter and vector triplet dark matter models. Our procedure is validated by using the same wino and Higgsino benchmark models employed by the ATLAS Collaboration. We have found that with the disappearing track signature, one can probe a vast portion of the parameter space, well beyond the reach of prompt missing energy searches (notably monojets). We provide tables with the upper limits on the cross section and efficiencies in the lifetime-a dark matter mass plane for all the models under consideration, which can be used for an easy recast for similar classes of models. Moreover, we provide the recasting code employed here, as part of the public LLP recasting repository.

Automated summary

This study reinterprets the latest ATLAS disappearing track search for a range of dark matter multiplets with different spins and electroweak quantum numbers, finding that the disappearing track signature can probe a vast portion of the parameter space. The results provide upper limits on the cross section and efficiencies in the lifetime-dark matter mass plane for all considered models, demonstrating the potential for easy recasting for similar classes of models. The recasting code employed in the study is also provided as part of the public LLP recasting repository.