Dark matter production through loop-induced processes at the LHC: the s-channel mediator case

We show how studies relevant for mono-X searches at the LHC in simplified models featuring a dark matter candidate and an $s$-channel mediator can be performed within the MadGraph5_aMC@NLO framework. We focus on gluon-initiated loop-induced processes, mostly relevant to the case where the mediator couples preferentially to third generation quarks and in particular to the top quark. Our implementation allows us to study signatures at hadron colliders involving missing transverse energy plus jets or plus neutral bosons ($\gamma,Z,H$), possibly including the effects of extra radiation by multi-parton merging and matching to the parton shower.