Hunting for dark matter coannihilation by mixing dijet resonances and missing transverse energy

Abstract

Simplified models of the dark matter (co)annihilation mechanism predict striking new collider signatures untested by current searches. These models, which were codified in the coannihilation codex, provide the basis for a dark matter (DM) discovery program at the Large Hadron Collider (LHC) driven by the measured DM relic density. In this work, we study an exemplary model featuring s-channel DM coannihilation through a scalar diquark mediator as a representative case study of scenarios with strongly interacting coannihilation partners. We discuss the full phenomenology of the model, ranging from low energy flavor constraints, vacuum stability requirements, and precision Higgs effects to direct detection and indirect detection prospects. Moreover, motivated by the relic density calculation, we find significant portions of parameter space are compatible with current collider constraints and can be probed by future searches, including a proposed analysis for the novel signature of a dijet resonance accompanied by missing transverse energy (MET). Our results show that the 13 TeV LHC with 100 fb −1 luminosity should be sensitive to mediators as heavy as 1 TeV and dark matter in the 400-500 GeV range. The combination of searches for single and paired dijet peaks, non-resonant jets + MET excesses, and our novel resonant dijet + MET signature have strong coverage of the motivated relic density region, reflecting the tight connections between particles determining the dark matter abundance and their experimental signatures at the LHC.

Simplified phenomenology for colored dark sectors

“…In this scenario the collider phenomenology is largely dominated by the multi-jet plus large missing transverse energy (MET) searches [38][39][40][41][42][43][44][45]. The sensitivity to direct and indirect dark matter searches is very weak, as discussed in [46]. The relic density prediction is dominated by X annihilation, which opens up seemingly excluded parameter space in DM mass or allows for less fine-tuning in the DM − X mass splitting than for electroweak coannihilation models.…”

“…The collider signatures of simplified models of coannihilating dark matter have been classified in [24] for all possible choices of quantum numbers of X. In reference [46] we explored the phenomenology of dark matter models where X is colored and the coannihilation process occurs through an s-channel mediator. These scenarios lead to a wide variety of characteristic collider signatures, notably from mediator single and pair-production.…”

Off-diagonal dark-matter phenomenology: Exploring enhanced complementarity relations in nonminimal dark sectors

“…For larger values of Δm, however, the decay of the heavier component is more rapid and can thus occur within the detection volume. Such scenarios have been considered in the context of colliders [53][54][55][56][57][58][59] as well as fixed-target experiments [60,61]. Key features of these scenarios are the detection of Standard-Model particles arising from the decay of the heavier dark particle, potentially with a displaced vertex.…”

A tale of two portals: testing light, hidden new physics at future e + e − colliders

“…On the other hand, dark matter coupled to kinetically mixed hidden photons suffers from strong direct detection constraints (see, e.g., [41]). A consistent dark matter model must hence simultaneously address the relic density mechanism and non-observation in the current experimental probes, and thus minimal models either require nonthermal dark matter production in the early universe, coannihilation channels [42][43][44], or resonant dark matter annihilation in order to divorce the early universe dynamics from collider processes (see, e.g., [45]). Moreover, while the nuclear recoil energy spectrum at direct detection experiments requires the dark matter JHEP06(2017)077 mass as input, colliders instead probe mediator masses if they are on-shell, which shows the complementarity between both approaches.…”