LHC Bounds on Interactions of Dark Matter

TL;DR

This work develops a minimal-flavor-violation, effective-field-theory framework for dark matter–quark interactions and derives LHC jet + missing-energy bounds on the suppression scale $M_*$ as a function of the DM mass $m_χ$ for several operators. It connects collider limits to direct-detection observables by providing explicit SI and SD cross-section expressions and analyzes isospin-violating couplings, showing that 7 TeV LHC data can be competitive with direct-detection bounds for light DM, while future 14 TeV reach extends sensitivity. The study finds that collider constraints are particularly strong when DM is light and that isospin-violating scenarios can change the relative strength of collider versus direct-detection limits, depending on the operator structure and quark couplings. The results hinge on the assumption of a heavy mediator and MFV; to reconcile CoGeNT with Xenon, either a light mediator or more complex flavor structure is required, indicating the need for UV-complete models or modified coupling patterns.

Abstract

We derive limits on the interactions of dark matter with quarks from ATLAS null searches for jets + missing energy based on ~1 fb^-1 of integrated luminosity, using a model-insensitive effective theory framework. We find that the new limits from the LHC significantly extend limits previously derived from CDF data at the Tevatron. Translated into the parameter space of direct searches, these limits are particularly effective for ~GeV mass WIMPs. Our limits indicate tension with isospin violating models satisfying minimal flavor violation which attempt to reconcile the purported CoGeNT excess with Xenon-100, indicating that either a light mediator or nontrivial flavor structure for the dark sector is necessary for a viable reconciliation of CoGeNT with Xenon.

Figures (11)

• Figure 1: The collider bounds on the down-type quark operators with scalar Lorentz structures. Operators M1d, M2d, M3d, M4d, are in red, blue, green, and black respectively. The dashed-dotted, dashed, and solid lines are the Tevatron constraints, LHC constraints, and LHC discovery reach. The shaded region is where the effective theory breaks down. Models M1d and M3d are largely degenerate, as are models M2d and M4d.
• Figure 2: The same as Fig. \ref{['fig:csd']}, for up-type quark operators M1u, M2u, M3u, and M4u.
• Figure 3: The collider bounds on the down-type quark coupling operators mediated by a heavy scalar. Models M5d, M6d are in red, black respectively. The dashed-dotted, dashed, and solid lines are the Tevatron constraints, LHC constraints, and LHC discovery reach. The shaded region is where the effective theory breaks down. Models M5d and M6d are largely degenerate.
• Figure 4: The same as Fig. \ref{['fig:cvd']}, although now the up-type quark coupling operators M5u and M6u are displayed.
• Figure 5: Spin-dependent nucleon scattering cross section assuming only the up-type quark operator M6u is present. The red and blue lines are the constraints from the Tevatron search and 7 TeV LHC search. The green lines are the 14 TeV LHC discovery reach. The solid lines are the proton coupling cross section and the dotted lines are the neutron coupling cross section. The dashed black line is the Xenon 10 constraint on the neutron cross section Angle:2007uj and the solid black line is the SIMPLE constraint on the proton cross section Felizardo:2010mi.