Beyond effective field theory for dark matter searches at the LHC

• Published in: The journal of high energy physics Vol. 2014; no. 1; pp. 1 - 24
• Main Authors: Buchmueller, O., Dolan, Matthew J., McCabe, Christopher
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 2014; Springer Nature B.V
• Subjects: Aircraft detection; Classical and Quantum Gravitation; Consistency; Contact; Dark matter; Density; Elementary Particles; Field theory; High energy physics; Mathematical analysis; Physics; Physics and Astronomy; Quantum Field Theories; Quantum Field Theory; Quantum Physics; Relativity Theory; Searching; String Theory; Hadron-Hadron Scattering; Exotics
• ISSN: 1029-8479; 1029-8479
• DOI: 10.1007/JHEP01(2014)025

A bstract We study the validity of effective field theory (EFT) interpretations of monojet searches for dark matter at the LHC for vector and axial-vector interactions. We show that the EFT approach is valid when the mediator has mass m med greater than 2.5 TeV. We find that the current limits on the contact interaction scale Λ in the EFT apply to theories that are perturbative for dark matter mass m DM   <  800 GeV. However, for all values of m DM in these theories, the mediator width is larger than the mass, so that a particle-like interpretation of the mediator is doubtful. Furthermore, consistency with the thermal relic density occurs only for 170 ≲ m DM ≲ 510 GeV. For lighter mediator masses, the EFT limit either under-estimates the true limit (because the process is resonantly enhanced) or over-estimates it (because the missing energy distribution is too soft). We give some ‘rules of thumb’ that can be used to estimate the limit on Λ (to an accuracy of ~ 50 %) for any m DM and m med from knowledge of the EFT limit. We also compare the relative sensitivities of monojet and dark matter direct detection searches finding that both dominate in different regions of the m DM - m med plane. Comparing only the EFT limit with direct searches is misleading and can lead to incorrect conclusions about the relative sensitivity of the two search approaches.