Anomaly detection search for new resonances decaying into a Higgs boson and a generic new particle $X$ in hadronic final states using $\sqrt{s}=13$ TeV $pp$ collisions with the ATLAS detector

Abstract

A search is presented for a heavy resonance $Y$ decaying into a Standard Model Higgs boson $H$ and a new particle $X$ in a fully hadronic final state. The full Large Hadron Collider Run 2 dataset of proton-proton collisions at $\sqrt{s}=13$ TeV collected by the ATLAS detector from 2015 to 2018 is used, and corresponds to an integrated luminosity of 139 fb${}^{-1}$. The search targets the high $Y$-mass region, where the $H$ and $X$ have a significant Lorentz boost in the laboratory frame. A novel signal region is implemented using anomaly detection, where events are selected solely because of their incompatibility with a learned background-only model. It is defined using a jet-level tagger for signal-model-independent selection of the boosted $X$ particle, representing the first application of fully unsupervised machine learning to an ATLAS analysis. Two additional signal regions are implemented to target a benchmark $X$ decay into two quarks, covering topologies where the $X$ is reconstructed as either a single large-radius jet or two small-radius jets. The analysis selects Higgs boson decays into $b\bar{b}$, and a dedicated neural-network-based tagger provides sensitivity to the boosted heavy-flavor topology. No significant excess of data over the expected background is observed, and the results are presented as upper limits on the production cross section $\sigma (pp\to Y\to XH\to q\bar{q}b\bar{b}$) for signals with $m_Y$ between 1.5 and 6 TeV and $m_X$ between 65 and 3000 GeV.

arXiv comment47 pages in total, author list starting page 30, 13 figures, 1 table. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HDBS-2019-23/

References in corpus (41)

• Observation of a new particle in the search for the Standard Model Higgs boson with the ATLAS detector at the LHC
• Observation of a new boson at a mass of 125 GeV with the CMS experiment at the LHC
• A Large Mass Hierarchy from a Small Extra Dimension
• The automated computation of tree-level and next-to-leading order differential cross sections, and their matching to parton shower simulations
• The anti-k_t jet clustering algorithm
• A Brief Introduction to PYTHIA 8.1
• FastJet user manual
• Theory and phenomenology of two-Higgs-doublet models
• The ATLAS Simulation Infrastructure
• PDF4LHC recommendations for LHC Run II
• Identifying Boosted Objects with N-subjettiness
• On Kaluza-Klein States from Large Extra Dimensions
• Jet Trimming
• Production and Integration of the ATLAS Insertable B-Layer
• Topological cell clustering in the ATLAS calorimeters and its performance in LHC Run 1
• Luminosity determination in pp collisions at $\sqrt{s}$ = 8 TeV using the ATLAS detector at the LHC
• ATLAS $b$-jet identification performance and efficiency measurement with $t\bar{t}$ events in $pp$ collisions at $\sqrt{s}=13$ TeV
• Jet reconstruction and performance using particle flow with the ATLAS Detector
• Impact of Heavy Quark Masses on Parton Distributions and LHC Phenomenology
• ATLAS data quality operations and performance for 2015-2018 data-taking
• Jet energy scale and resolution measured in proton-proton collisions at $\sqrt{s}=13$ TeV with the ATLAS detector
• Searching for New Physics with Deep Autoencoders
• Power Counting to Better Jet Observables
• Heavy Vector Triplets: Bridging Theory and Data
• QCD or What?
• Adversarially-trained autoencoders for robust unsupervised new physics searches
• Performance of jet substructure techniques for large-R jets in proton-proton collisions at sqrt(s) = 7 TeV using the ATLAS detector
• Dijet resonance search with weak supervision using $\sqrt{s}=13$ TeV $pp$ collisions in the ATLAS detector
• Variational Autoencoders for New Physics Mining at the Large Hadron Collider
• The Dark Machines Anomaly Score Challenge: Benchmark Data and Model Independent Event Classification for the Large Hadron Collider
• Jets with Variable R
• Variational Autoencoders for Anomalous Jet Tagging
• Tagging a jet from a dark sector with Jet-substructures at colliders
• Bump Hunting in Latent Space
• Combining searches of Z' and W' bosons
• LHC Signals from Cascade Decays of Warped Vector Resonances
• Search for diboson resonances in hadronic final states in 139 fb${}^{-1}$ of $pp$ collisions at $\sqrt{s}=13$ TeV with the ATLAS detector
• E Pluribus Unum Ex Machina: Learning from Many Collider Events at Once
• Search for resonances decaying into a weak vector boson and a Higgs boson in the fully hadronic final state produced in proton$-$proton collisions at $\sqrt{s}=13$ TeV with the ATLAS detector
• A search for resonances decaying into a Higgs boson and a new particle $X$ in the $XH\to qqbb$ final state with the ATLAS detector
• Search for new heavy resonances decaying to WW, WZ, ZZ, WH, or ZH boson pairs in the all-jets final state in proton-proton collisions at $\sqrt{s}$ = 13 TeV

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