Higher-order QCD predictions for dark matter production at the LHC in simplified models with s-channel mediators

Abstract

Weakly interacting dark matter particles can be pair-produced at colliders and detected through signatures featuring missing energy in association with either QCD/EW radiation or heavy quarks. In order to constrain the mass and the couplings to standard model particles, accurate and precise predictions for production cross sections and distributions are of prime importance. In this work, we consider various simplified models with s-channel mediators. We implement such models in the FeynRules/MadGraph5_aMC@NLO framework, which allows to include higher-order QCD corrections in realistic simulations and to study their effect systematically. As a first phenomenological application, we present predictions for dark matter production in association with jets and with a top-quark pair at the LHC, at next-to-leading order accuracy in QCD, including matching/merging to parton showers. Our study shows that higher-order QCD corrections to dark matter production via s-channel mediators have a significant impact not only on total production rates, but also on shapes of distributions. We also show that the inclusion of next-to-leading order effects results in a sizeable reduction of the theoretical uncertainties.

Simplified dark matter models with a spin-2 mediator at the LHC

“…The event rate is normalised to the pp → Y 2 j NLO cross sections shown in Fig. 3. (Note, however, that NLO corrections may also affect the shapes of the kinematic distributions, as shown for the spin-1 and spin-0 cases in [17]; a detailed study of this aspect will be reported elsewhere. )…”

“…This work follows the DMsimp framework [16][17][18], which provides the DM model files for event generators such as MadGraph5_aMC@NLO [19] as well as for DM tools such as micrOMEGAs [20][21][22] and MadDM [23,24]. The same framework was used previously to study the cases of s-channel spin-1 and spin-0 mediators.…”

The waning of the WIMP? A review of models, searches, and constraints

“…This idea is at the base of the so-called "Simplified Models" [140][141][142][143][144][145][146][147][148][149][150][151][152][153][154] which are customarily adopted especially in the context of collider studies, see e.g., Refs. [130,[155][156][157][158][159][160][161][162][163][164][165][166].…”

The coannihilation codex

“…Therefore, in the recent literature simplified models are gaining in importance [12,[70][71][72][73][74][75][76][77]. The usefulness of EFTs and simplified models is illustrated by studies of higher order QCD corrections to DM production at the LHC [78][79][80][81]. These studies show that higher order effects can be very important, but computing them for every single UVcomplete model is clearly impractical.…”