Non-abelian dark sectors and their collider signatures

Abstract

Motivated by the recent proliferation of observed astrophysical anomalies, Arkani-Hamed et al. have proposed a model in which dark matter is charged under a nonabelian "dark" gauge symmetry that is broken at ∼ 1 GeV. In this paper, we present a survey of concrete models realizing such a scenario, followed by a largely model-independent study of collider phenomenology relevant to the Tevatron and the LHC. We address some model building issues that are easily surmounted to accommodate the astrophysics. While SUSY is not necessary, we argue that it is theoretically well-motivated because the GeV scale is automatically generated. Specifically, we propose a novel mechanism by which mixed D-terms in the dark sector induce either SUSY breaking or a super-Higgs mechanism precisely at a GeV. Furthermore, we elaborate on the original proposal of Arkani-Hamed et al. in which the dark matter acts as a messenger of gauge mediation to the dark sector. In our collider analysis we present cross-sections for dominant production channels and lifetime estimates for primary decay modes. We find that dark gauge bosons can be produced at the Tevatron and the LHC, either through a process analogous to prompt photon production or through a rare Z decay channel. Dark gauge bosons will decay back to the SM via "lepton jets" which typically contain > 2 and as many as 8 leptons, significantly improving their discovery potential. Since SUSY decays from the MSSM will eventually cascade down to these lepton jets, the discovery potential for direct electroweak-ino production may also be improved. Exploiting the unique kinematics, we find that it is possible to reconstruct the mass of the MSSM LSP. We also present several non-SUSY and SUSY decay channels that have displaced vertices and lead to multiple leptons with partially correlated impact parameters.

Decaying into the hidden sector

“…Supersymmetric kinetic mixing of this size automatically generates the GeV scale in the dark sector [3,27]. To see this, we expand Eq.…”

“…In practice, non-Abelian dark sectors are more difficult to construct and often require elaborate Higgs sectors [3]. In the explicit models that we study below, we will instead focus on the simplest possibility of a U (1) d hidden sector at low energies.…”

“…A splitting can be generated radiatively or through Yukawa interactions, as we discuss in section 2.6. Radiative splittings are generated after breaking non-Abelian dark sectors with specific matter content, however such models are significantly more complicated to construct [3]. A simpler alternative, when the DM is charged under U (1) d , is to couple it directly to the light Higgses, as in Eq.…”

“…Hidden sector particles can be produced in high energy colliders, as stressed in the context of 'Hidden Valley' models [1] and models where gauge kinetic mixing results in 'lepton jets' [2,3]. Such hidden sectors can also be probed with low energy e + e − colliders and fixed target experiments [4].…”

“…The TeV scale generates the DM mass which can be naturally related to the supersymmetry (SUSY) breaking scale, thereby avoiding the usual µ-problem. The GeV scale which controls the branching fractions of the DM decays into SM fields, is generated either by communicating supersymmetry breaking to the dark sector indirectly through the SM [2] or through D-term mixing [3,26,27]. Finally, splittings between DM states may be required to avoid direct detection.…”