Light dark matter and $Z'$ dark force at colliders

TL;DR

This paper explores collider-based searches for light dark matter mediated by a new $Z'$ gauge boson, demonstrating that resonance searches are more effective than monojet channels for certain mass ranges.

Contribution

It introduces a combined collider search strategy for light dark matter with a $Z'$ mediator, highlighting the effectiveness of resonance searches over monojet channels.

Findings

Resonance searches outperform monojet+MET searches for $Z'$ masses 250 GeV to 4 TeV.

Collider constraints are stronger than direct detection for this model.

The $Z'$ mediator can be probed effectively through dijet resonance searches.

Abstract

Light Dark Matter, $<10$ GeV, with sizable direct detection rate is an interesting and less explored scenario. Collider searches can be very powerful, such as through the channel in which a pair of dark matter particle are produced in association with a jet. It is a generic possibility that the mediator of the interaction between DM and the nucleus will also be accessible at the Tevatron and the LHC. Therefore, collider search of the mediator can provide a more comprehensive probe of the dark matter and its interactions. In this article, to demonstrate the complementarity of these two approaches, we focus on the possibility of the mediator being a new $U(1)'$ gauge boson, which is probably the simplest model which allows a large direct detection cross section for a light dark matter candidate. We combine searches in the monojet+MET channel and dijet resonance search for the mediator. We find that for the mass of $Z'$ between 250 GeV and 4 TeV, resonance searches at the colliders provide stronger constraints on this model than the monojet+MET searches.