Constraints on Light Majorana Dark Matter from Colliders

TL;DR

The paper develops a model-independent EFT framework to constrain light Majorana DM via collider processes, focusing on ten operators that couple a SM-singlet WIMP to SM fields. By analyzing Tevatron monojet data and projecting LHC reach, the authors map collider cross-section limits to the operator scale $M_*$ and then to direct-detection cross sections for select operators. They show that collider constraints can be stronger than current or near-future direct-detection limits for $m_\chi$ in the GeV range, especially for interactions suppressed at low momentum transfer, and provide critical insight into the viability of low-mass DM scenarios such as those motivated by DAMA and CoGeNT. The work highlights the complementary role of collider searches in probing DM interactions inaccessible to direct detection and delineates the EFT validity regime for interpreting collider results.

Abstract

We explore model-independent collider constraints on light Majorana dark matter particles. We find that colliders provide a complementary probe of WIMPs to direct detection, and give the strongest current constraints on light DM particles. Collider experiments can access interactions not probed by direct detection searches, and outperform direct detection experiments by about an order of magnitude for certain operators in a large part of parameter space. For operators which are suppresssed at low momentum transfer, collider searches have already placed constraints on such operators limiting their use as an explanation for DAMA.

Figures (6)

• Figure 1: Constraints on $M_*$ for operators M1-M4. Solid lines are Tevatron 2$\sigma$ constraints. Dashed lines show LHC 5$\sigma$ reach. Results for M1 and M2 are largely degenerate with M3 and M4, respectively. The dash-dotted lines show the value of $M_*$ which reproduce the thermal relic density ($\Omega h^2 = 0.11$). In the shaded region, the effective theory breaks down.
• Figure 2: Same as Fig. \ref{['fig:1-4']}, but for the largely degenerate operators M5 and M6.
• Figure 3: Same as Fig. \ref{['fig:1-4']}, but for the operators M7 and M8 which are largely degenerate with M9 and M10, respectively.
• Figure 4: Regions of parameter space excluded by Tevatron searches, CDMS/Xenon 10 Ahmed:2009zwAngle:2007uj, CoGeNT Aalseth:2008, and CRESST Angloher:2002in (solid lines as indicated). The shaded region is the parameter space favored by a WIMP interpretation of the CoGeNT signal Aalseth:2010vx. Also shown are projected bounds for for the LHC, (S)CDMS Akerib:2006, and Xenon 100 Aprile:2009yh (dotted lines as indicated).
• Figure 5: Regions of parameter space excluded by Tevatron searches, Xenon 10 Angle:2007uj, KIMS Lee:2007 and PICASSO Archambault:2009. Also shown are projected bounds for the LHC and DMTPC Sciolla:2009.