Distinguishing dynamical dark matter at the LHC

Abstract

Dynamical dark matter (DDM) is a new framework for dark-matter physics in which the dark sector comprises an ensemble of individual component fields which collectively conspire to act in ways that transcend those normally associated with dark matter. Because of its non-trivial structure, this DDM ensemble -unlike most traditional dark-matter candidates -cannot be characterized in terms of a single mass, decay width, or set of scattering cross-sections, but must instead be described by parameters which describe the collective behavior of its constituents. Likewise, the components of such an ensemble need not be stable so long as lifetimes are balanced against cosmological abundances across the ensemble as a whole. In this paper, we investigate the prospects for identifying a DDM ensemble at the LHC and for distinguishing such a dark-matter candidate from the candidates characteristic of traditional dark-matter models. In particular, we focus on DDM scenarios in which the component fields of the ensemble are produced at colliders alongside some number of Standard-Model particles via the decays of additional heavy fields. The invariant-mass distributions of these Standard-Model particles turn out to possess several unique features that cannot be replicated in most traditional dark-matter models. We demonstrate that in many situations it is possible to differentiate between a DDM ensemble and a traditional dark-matter candidate on the basis of such distributions. Moreover, many of our results also apply more generally to a variety of other extensions of the Standard Model which involve multiple stable or metastable neutral particles.

Strategies for probing nonminimal dark sectors at colliders: The interplay between cuts and kinematic distributions

“…For example, it has been shown that DDM ensembles can give rise to statistically significant deviations from the kinematic distributions associated with traditional, single-particle dark-matter candidates at colliders [6], at direct-detection experiments [7], and at cosmicray detectors [8]. Similar analyses have also been performed for other non-minimal dark-matter scenarios in the context of direct detection [4], indirect detection [9], and collider searches [10][11][12].…”

“…Indeed, as was noted in Ref. [6] in the case of three-body parent-particle decays, there exists a particular intermediate range of γ for any particular assignment of m 0 , ∆m, etc., within which the branching fractions of φ to two or more of the χ n are of roughly the same order and the corresponding kinematic distributions are therefore more distinctive.…”

“…To do this, we shall adopt a procedure similar to that employed in Ref. [6]. In particular, we survey over a variety of traditional dark-matter candidates, each characterized by a different value of m χ , and compare the distribution of that variable with the distribution obtained for the DDM ensemble of interest.…”

Beyond the bump-hunt: A game plan for discovering dynamical dark matter at the LHC

“…For example, in cases in which each parent particle decays to a single ensemble constituent and a pair of hadronic jets, we find that the invariant-mass distribution of these two jets could provide a distinctive signal of Dynamical Dark Matter [3]. Similarly, in cases in which the parent particle decays primarily into a single ensemble constituent and a single jet, we find that the M T 2 distribution can likewise provide such a signal [4].…”

Dynamical Dark Matter from strongly-coupled dark sectors

“…Quantities such as the total energy density Ω CDM and the effective equation-of-state parameter w eff are thus timedependent quantities, and it is only an accident that these quantities happen to take particular values at the present time. Many methods have been developed for testing this framework, spanning from collider signatures [3,4] to signatures in direct-detection [5] and indirect-detection [6][7][8] experiments.…”