Maverick dark matter at colliders

Abstract: Assuming that dark matter is a weakly interacting massive particle (WIMP) species X produced in the early Universe as a cold thermal relic, we study the collider signal of pp or ppbar -> XXbar + jets and its distinguishability from standard-model background processes associated with jets and missing energy. We assume that the WIMP is the sole particle related to dark matter within reach of the LHC--a "maverick" particle--and that it couples to quarks through a higher dimensional contact interaction. We simulate the WIMP final-state signal XXbar + jet and dominant standard-model (SM) background processes and find that the dark-matter production process results in higher energies for the colored final state partons than do the standard-model background processes, resulting in more QCD radiation and a higher jet multiplicity. As a consequence, the detectable signature of maverick dark matter is an excess over standard-model expectations of events consisting of large missing transverse energy, together with large leading jet transverse momentum and scalar sum of the transverse momenta of the jets. Existing Tevatron data and forthcoming LHC data can constrain (or discover!) maverick dark matter.

• The paper demonstrates that collider signals with large missing energy and high-pT jets can effectively probe maverick dark matter candidates.
• The paper employs an effective field theory framework with axial-vector couplings to model the interaction between a fermionic WIMP and standard model quarks.
• The paper shows that optimized kinematic cuts enable potential detection of WIMPs up to 15 GeV at Tevatron and 275 GeV at the LHC.

An Examination of Maverick Dark Matter Detection at High-Energy Colliders

This paper presents a rigorous study of the detection prospects for a specific type of dark matter candidate, conceptualized as a "maverick" dark matter particle, at high-energy collider experiments such as the Tevatron and the Large Hadron Collider (LHC). The maverick dark matter particle is assumed to be a weakly interacting massive particle (WIMP) produced as a cold thermal relic during the early Universe. The authors propose that it is the only new particle species beyond the standard model (SM) that would be accessible at the LHC, unlike typical assumptions within specific theoretical frameworks such as supersymmetry or models incorporating extra dimensions.

Model Framework

The consideration of maverick dark matter in this study relies on an effective field theory (EFT) approach, where the interaction of the WIMP with SM quarks is described by higher-dimensional contact interactions. This setup allows the exploration of general properties without committing to a specific underlying theory beyond the standard model, thus remaining agnostic regarding the larger theoretical context it belongs to.

In particular, the paper focuses on a fermionic WIMP candidate with axial-vector couplings to quarks, which potentially evades direct detection constraints due to the nature of spin-dependent interactions. This marks an effective use of a theoretically motivated scenario to explore unexplored territories in the context of dark matter detection and collider phenomenology.

Collider Signal Analysis

A central aspect of the analysis involves simulating the collider signal of dark matter pair production in association with jets. This process is represented as $pp$ (or $p\bar{p}$) $\rightarrow X \bar{X} + \text{jets}$, where $X$ denotes the maverick dark matter particle. The focus is on large missing transverse energy (MET) and high transverse momentum jets as key indicators that can differentiate dark matter signals from standard-model backgrounds such as $Z$ or $W$ bosons decaying into jets and neutrinos, which are invisible to the detector.

Numerical Results and Discovery Potential

Numerical simulations conducted in this research indicate that the characteristic collider signature for maverick dark matter is an energy spectrum of jets that exceeds the expectations from SM processes. Various cuts on observable parameters—most notably jet transverse momentum and missing energy—are applied to optimize signal-background discrimination.

The study concludes that with the assumed capabilities of the Tevatron and LHC, maverick dark matter candidates with certain mass ranges could be detected, or constraints could be placed. At the Tevatron with an integrated luminosity of $10 \, \text{fb}^{-1}$, WIMP masses up to approximately $15 \, \text{GeV}$ might be discernible. Meanwhile, the LHC, benefiting from its higher energy and luminosity conditions, could extend this reach up to $275 \, \text{GeV}$.

Implications and Speculative Remarks

The paper suggests that this framework for analyzing maverick dark matter is robust and could indeed yield significant insights and constraints on the nature of dark matter from collider experiments. It also highlights the importance of cross-referencing indirect signs from colliders with results from direct or indirect dark matter detection experiments. Future experimental data could further validate the EFT approach used here, or necessitate modifications to include additional particles or interactions. Such studies pave the way for a deeper understanding of dark matter, aligning cosmic observations with terrestrial experimental physics, ultimately advancing the frontier in astroparticle physics.