Abstract
We outline and investigate a set of benchmark simplified models with the aim of providing a minimal simple framework for an interpretation of the existing and forthcoming searches of dark matter particles at the LHC. The simplified models we consider provide microscopic QFT descriptions of interactions between the Standard Model partons and the dark sector particles mediated by the four basic types of messenger fields: scalar, pseudo-scalar, vector or axial-vector. Our benchmark models are characterised by four to five parameters, including the mediator mass and width, the dark matter mass and an effective coupling(s). In the gluon fusion production channel we resolve the top-quark in the loop and compute full top-mass effects for scalar and pseudo-scalar messengers. We show the LHC limits and reach at 8 and 14 TeV for models with all four messenger types. We also outline the complementarity of direct detection, indirect detection and LHC bounds for dark matter searches. Finally, we investigate the effects which arise from extending the simplified model to include potential new physics contributions in production. Using the scalar mediator as an example we study the impact of heavy new physics loops which interfere with the top mediated loops. Our computations are performed within the MCFM framework and we provide fully flexible public Monte Carlo implementation.
Highlights
Many extensions of the Standard Model (SM) predict the existence of dark particles that can be produced in collisions of ordinary matter but are not directly measurable in the LHC’s multipurpose experiments
Dark particles constitute the dark sector, which plays a special role in any comprehensive beyond-the-StandardModel (BSM) description of particle physics: some of the dark sector particles can be cosmologically stable,1 and as such they give rise to the dark matter
The results of this paper extend the existing dark matter processes in MCFM [6], which focused primarily on NLO corrections in the effective field theory approach
Summary
Many extensions of the Standard Model (SM) predict the existence of dark particles that can be produced in collisions of ordinary matter but are not directly measurable in the LHC’s multipurpose experiments. The simplified model framework for dark matter and dark sector searches at colliders should constitute a list of key relevant QFT interactions which first produce a mediator particle in a proton-proton collision which subsequently decays into other particles, including dark matter Such benchmark models would be characterized by the production mechanism (e.g. qqor gluon-gluon, etc.), the type of the mediator (e.g. scalar, pseudoscalar, vector or axial vector) and the decay channel (e.g. s-channel or t-channel production of two dark matter fermions, or other DM particle species). [2] have discussed examples of tree-level benchmark processes relevant for interpreting DM searches at colliders, quark-antiquark s-channel processes mediated by scalar ðSÞsqqand vector ðVÞsqqmessengers, and the t-channel processes mediated by colored scalar ðCSÞtqqmessengers They have considered gluon fusion via dimension-5 effective field theory (EFT) operators mediated by scalar ðSÞEggFT and pseudoscalar messengers ðPÞEggFT and have commented on EFT models in which DM coupled preferentially to the third generation.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
