Performance of jet substructure techniques for large-R jets in proton-proton collisions at $ \sqrt{s}=7 $ TeV using the ATLAS detector

Abstract

This paper presents the application of a variety of techniques to study jet substructure. The performance of various modified jet algorithms, or jet grooming techniques, for several jet types and event topologies is investigated for jets with transverse momentum larger than 300 GeV. Properties of jets subjected to the mass-drop filtering, trimming, and pruning algorithms are found to have a reduced sensitivity to multiple proton-proton interactions, are more stable at high luminosity and improve the physics potential of searches for heavy boosted objects. Studies of the expected discrimination power of jet mass and jet substructure observables in searches for new physics are also presented. Event samples enriched in boosted W and Z bosons and top-quark pairs are used to study both the individual jet invariant mass scales and the efficacy of algorithms to tag boosted hadronic objects. The analyses presented use the full 2011 ATLAS dataset, corresponding to an integrated luminosity of 4.7 ± 0.1 fb −1 from proton-proton collisions produced by the LargeHadron Collider at a centre-of-mass energy of √ s = 7 TeV. Keywords: Hadron-Hadron ScatteringArXiv ePrint: 1306.4945Open Access, Copyright CERN, for the benefit of the ATLAS collaboration Conclusions 58The ATLAS collaboration 67-1 - JHEP09(2013)0761 IntroductionThe dominant feature of high-energy proton-proton (pp) collisions at the Large Hadron Collider (LHC) is the production of highly collimated sprays of energetic hadrons, called jets, that originate from the quarks and gluons in the primary collisions. The large centreof-mass energy at the LHC enables the production of Lorentz-boosted heavy particles, whose decay products can be reconstructed as one large-area jet. The study of the internal structure of jets goes beyond the four-momentum description of a single parton and yields new approaches for testing Quantum Chromodynamics (QCD) and for searching for new physics in hadronic final states. However, many of the new tools developed for the study of jet substructure at the LHC have only recently been validated with data in a hadron-hadron collider environment. For example, the effect of multiple pp interactions on large-area jet measurements has not been extensively studied experimentally. This paper presents a comprehensive set of studies designed to establish the efficacy, accuracy, and precision of several of the tools available for determining and analysing the internal structure of jets at the LHC. New jet algorithms and strategies, referred to as jet grooming, that refine the definition of a jet in a high-luminosity environment, are studied using data taken at a centre-of-mass energy of √ s = 7 TeV during 2011. A variety of techniques and tagging algorithms intended to improve the mass resolution in the reconstruction of boosted objects that decay hadronically are studied in the data both in inclusive jet samples and in samples enriched in events containing boosted W /Z bosons and top quarks. Evaluations of the systematic uncertainties for jet m...

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