Constraints on New Scalar and Vector Mediators from LHC Dijet Searches.

We present a reanalysis of the latest results from CMS dijet searches for an integrated luminosity of $36$ fb$^{-1}$ together with preliminary results for $78$ fb$^{-1}$ in the framework of simplified models for dark matter interacting with quarks through the exchange of a scalar, pseudoscalar, vector or pseudovector mediator particle.~Within the same framework, we also project the sensitivity of dijet searches in future LHC runs and study how well the parameters of a simplified model could be reconstructed in case of a future discovery at the high luminosity (HL) LHC.~Finally, we explore the possibility of discriminating different mediator scenarios by extending the sensitivity of dijet searches for simplified models through the use of angular information.~It is the first time that these studies are performed systematically for the case of spin 0 mediators.~Among other results we find:~1) no evidence for a dijet signal in the simplified model framework;~2) improvements due to an increased luminosity at the HL-LHC are significant, but mostly for heavy mediators, where dijet searches are limited by statistical, rather than systematical uncertainties;~3)~Information on the angular separation of dijets could be used at the HL-LHC to discriminate different mediator scenarios.