Searching for dark matter in final states with two jets and missing transverse energy

We reemphasise the usefulness of angular correlations in LHC searches for missing transverse energy (Emiss) signatures that involve jet (j) pairs with large invariant mass. For the case of mono-jet production via gluon-fusion, we develop a realistic analysis strategy that allows to split the dark matter (DM) signal into distinct one jet-like and two jet-like event samples. By performing state-of-the-art Monte Carlo simulations of both the mono-jet signature and the standard model background, it is shown that the dijet azimuthal angle difference phi j1j2 in 2j+ETmiss production provides a powerful discriminant in realistic searches. Employing a shape fit to phi j1j2, we then determine the LHC reach of the mono-jet channel in the context of spin-0 s-channel DM simplified models. The constraints obtained by the proposed phi j1j2 shape fit turn out to be significantly more stringent than those that derive from standard Emiss shape analyses.