Vector dark matter at the LHC

Abstract: We consider monojet searches at the Large Hadron Collider (LHC) for spin-1 dark matter that interacts with quarks through a contact operator. If the dark matter particles are produced with longitudinal polarizations, then the production matrix element is enhanced by factors of the energy. We show that this particularly effective search strategy can test models for which the energy suppression scale of the operator is as large as 10^5 TeV. As such, these searches can probe a large class of models for which the contact-operator approximation is valid. We find that for contact operators that permit velocity-independent dark matter-nucleon scattering, LHC monojet searches for spin-1 dark matter are competitive with or far surpass direct-detection searches depending on whether the scattering is spin independent or spin dependent, respectively.