Constraints on Dark Matter from Colliders (1008.1783v2)

Abstract: We show that colliders can impose strong constraints on models of dark matter, in particular when the dark matter is light. We analyze models where the dark matter is a fermion or scalar interacting with quarks and/or gluons through an effective theory containing higher dimensional operators which represent heavier states that have been integrated out of the effective field theory. We determine bounds from existing Tevatron searches for monojets as well as expected LHC reaches for a discovery. We find that colliders can provide information which is complementary or in some cases even superior to experiments searching for direct detection of dark matter through its scattering with nuclei. In particular, both the Tevatron and the LHC can outperform spin dependent searches by an order of magnitude or better over much of parameter space, and if the dark matter couples mainly to gluons, the LHC can place bounds superior to any spin independent search.

• The paper demonstrates that collider experiments can effectively constrain light dark matter models using effective field theory methods.
• It employs monojet search data from Tevatron and LHC simulations to establish bounds that surpass traditional spin-dependent detection limits.
• Results show that collider constraints, especially for gluon-coupled dark matter, complement direct detection efforts and inspire further research.

Constraints on Dark Matter from Colliders

The paper "Constraints on Dark Matter from Colliders," authored by Jessica Goodman et al., addresses the ability of collider experiments to impose constraints on dark matter models, particularly focusing on scenarios in which dark matter is light. The manuscript explores models where dark matter is a fermion or scalar interacting through an effective theory with quarks and gluons, delineated by higher-dimensional operators indicative of heavier states that are integrated out.

Core Analysis

The researchers delve into how constraints can be obtained from existing Tevatron monojet search results as well as projected LHC searches, demonstrating that collider data can offer complementary, or possibly superior, insights compared to traditional direct detection experiments aimed at identifying dark matter via nuclear scattering.

Significant findings include the assertion that both Tevatron and LHC facilities have the potential to outperform spin-dependent searches by an order of magnitude over most of the parameter space. Notably, if dark matter interacts primarily with gluons, the LHC can extend bounds beyond any spin-independent searches.

Methodological Approach

The paper employs a comprehensive framework of effective field theory operators to model the interactions between dark matter and the Standard Model (SM) particles. The dark matter candidates considered are either Dirac or Majorana fermions, and real or complex scalars. These particles couple to SM fields via operators, assuming a $Z_2$ parity that stabilizes the dark matter candidates. The operator analysis includes quark and gluon couplings, with interaction strengths weighed by inverse powers of a scale $M_*$ related to the mass and couplings of mediating particles.

Collider simulations were carried out using CompHEP, Pythia, and PGS, comparing theoretical predictions against CDF monojet data and LHC projected sensitivity. Efficiencies were evaluated to account for real-world hadronization and detector effects.

Implications for Direct Detection and Future Research

The theoretical implications presented in the paper highlight that collider constraints are particularly effective for low-mass dark matter candidates, where direct detection experiments are constrained by energy thresholds. The complementarity of collider and direct detection experiments presents a robust framework for ruling out or supporting particular mass and interaction regions for dark matter.

Furthermore, the paper advocates for further investigation into models with light mediator particles affecting collider bounds, suggesting an interest in dark matter models beyond effective field theory, potentially leading to novel detection methods and theoretical expansions.

Conclusion

"Constraints on Dark Matter from Colliders" offers a rigorous exploration of the potential for collider experiments to inform the parameter space of viable dark matter models. By effectively combining theoretical modeling, numerical simulations, and experimental data analysis, the work paves the way for deeper understanding in the ongoing search for dark matter, inspiring future investigations into unexplored regions of mass and interaction strength. The intersection of collider physics and dark matter detection emerges as a fertile ground for developing the standard model of cosmology and particle physics further.