Don't be left in the dark: Improving LHC searches for dark photons using lepton-jet substructure

Abstract

Collider signals of dark photons are an exciting probe for new gauge forces and are characterized by events with boosted lepton jets. Existing techniques are efficient in searching for muonic lepton jets but due to substantial backgrounds have difficulty constraining lepton jets containing only electrons. This is unfortunate since upcoming intensity frontier experiments are sensitive to dark photon masses which only allow electron decays. Analyzing a recently proposed model of kinetic mixing, with new scalar particles decaying into dark photons, we find that existing techniques for electron jets can be substantially improved. We show that using lepton-jet-substructure variables, in association with a boosted decision tree, improves background rejection, significantly increasing the LHC's reach for dark photons in this region of parameter space.

28 pages, 9 figures; v2. As appears in PRD. Added appendix to compare boosted decision tree to a cut-based analysis. Other minor typos corrected

References in corpus (12)

• PYTHIA 6.4 Physics and Manual
• The automated computation of tree-level and next-to-leading order differential cross sections, and their matching to parton shower simulations
• A Theory of Dark Matter
• Secluded WIMP Dark Matter
• FeynRules - Feynman rules made easy
• Jet substructure as a new Higgs search channel at the LHC
• Illuminating Dark Photons with High-Energy Colliders
• Jet substructure as a new Higgs search channel at the LHC
• Non-Abelian Dark Sectors and Their Collider Signatures
• Evidence for Electroweak Production of $W^{\pm }{W}^{\pm }jj$ in $pp$ Collisions at $\sqrt{s}=8$ TeV with the ATLAS Detector
• Discovering Higgs Decays to Lepton Jets at Hadron Colliders
• Jets and Photons