Evidence for $t\bar{t}t\bar{t}$ production in the multilepton final state in proton-proton collisions at $\sqrt{s}$=13 TeV with the ATLAS detector

Abstract

A search is presented for four-top-quark production using an integrated luminosity of 139 fb${}^{-1}$ of proton-proton collision data at a centre-of-mass energy of 13 TeV collected by the ATLAS detector at the LHC. Events are selected if they contain a same-sign lepton pair or at least three leptons (electrons or muons). Jet multiplicity, jet flavour and event kinematics are used to separate signal from the background through a multivariate discriminant, and dedicated control regions are used to constrain the dominant backgrounds. The four-top-quark production cross section is measured to be 24${}_{-6}^{+7}$ fb. This corresponds to an observed (expected) significance with respect to the background-only hypothesis of 4.3 (2.4) standard deviations and provides evidence for this process.

45 pages total, author list starting page 29, 7 figures, 4 tables, published in EPJC. All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/TOPQ-2018-05/

References in corpus (22)

• The automated computation of tree-level and next-to-leading order differential cross sections, and their matching to parton shower simulations
• An Introduction to PYTHIA 8.2
• Parton distributions for the LHC
• Matching NLO QCD computations with Parton Shower simulations: the POWHEG method
• Event generation with SHERPA 1.1
• Herwig++ Physics and Manual
• Parton distributions in the LHC era: MMHT 2014 PDFs
• A parton shower algorithm based on Catani-Seymour dipole factorisation
• Two-loop soft anomalous dimensions for single top quark associated production with a W- or H-
• Single-top hadroproduction in association with a W boson
• Next-to-next-to-leading-order collinear and soft gluon corrections for t-channel single top quark production
• NNLL resummation for s-channel single top quark production
• Electron and photon performance measurements with the ATLAS detector using the 2015-2017 LHC proton-proton collision data
• The PDF4LHC Working Group Interim Recommendations
• Combined measurements of Higgs boson production and decay using up to $80$ fb${}^{-1}$ of proton-proton collision data at $\sqrt{s}=$ 13 TeV collected with the ATLAS experiment
• Performance of electron and photon triggers in ATLAS during LHC Run 2
• Performance of the ATLAS muon triggers in Run 2
• The RooFit toolkit for data modeling
• tWH associated production at the LHC
• Search for production of four top quarks in final states with same-sign or multiple leptons in proton-proton collisions at $\sqrt{s}=$ 13 TeV
• Searching for sgluons in multitop events at a center-of-mass energy of 8 TeV
• Limiting Top-Higgs Interaction and Higgs-Boson Width from Multi-Top Productions

Cited by in corpus (43)

• Automated one-loop computations in the SMEFT
• Searches for the BSM scenarios at the LHC using decision tree based machine learning algorithms: A comparative study and review of Random Forest, Adaboost, XGboost and LightGBM frameworks
• Rare and Different: Anomaly Scores from a combination of likelihood and out-of-distribution models to detect new physics at the LHC
• Observation of four-top-quark production in the multilepton final state with the ATLAS detector
• Search for doubly and singly charged Higgs bosons decaying into vector bosons in multi-lepton final states with the ATLAS detector using proton-proton collisions at $\sqrt{s}$ = 13 TeV
• Unveiling Hidden Physics at the LHC
• Software and computing for Run 3 of the ATLAS experiment at the LHC
• Precise predictions for the associated production of a $W$ boson with a top-antitop quark pair at the LHC
• Search for pair production of third-generation scalar leptoquarks decaying into a top quark and a $\tau$-lepton in $pp$ collisions at $\sqrt{s}=13$ TeV with the ATLAS detector
• SPANet: Generalized Permutationless Set Assignment for Particle Physics using Symmetry Preserving Attention
• Les Houches 2021: Physics at TeV Colliders: Report on the Standard Model Precision Wishlist
• Top-quark pair production in association with a $W^{\pm }$ gauge boson in the POWHEG-BOX
• Two-Higgs-Doublet Model with Soft CP-violation Confronting Electric Dipole Moments and Colliders
• Observation of four top quark production in proton-proton collisions at $\sqrt{s}$ = 13 TeV
• Measurement of the $t\bar{t}t\bar{t}$ production cross section in $pp$ collisions at $\sqrt{s}$=13 TeV with the ATLAS detector
• Search for R-parity violating supersymmetry in a final state containing leptons and many jets with the ATLAS experiment using $\sqrt{s}=13$ TeV proton-proton collision data
• Modeling uncertainties of $t\bar{t}{W}^{\pm }$ multilepton signatures
• Combined SMEFT interpretation of Higgs, diboson, and top quark data from the LHC
• Multi-lepton probes of new physics and lepton-universality in top-quark interactions
• On the BSM reach of four top production at the LHC
• Evidence for four-top quark production in proton-proton collisions at $\sqrt{s}$ = 13 TeV
• Measurement of the energy response of the ATLAS calorimeter to charged pions from $W^{\pm }\to {\tau }^{\pm }(\to {\pi }^{\pm }{\nu }_{\tau }){\nu }_{\tau }$ events in Run 2 data
• Search for flavor-changing neutral-current couplings between the top quark and the $Z$ boson with proton-proton collisions at $\sqrt{s}=13$ TeV with the ATLAS detector
• Bayesian Probabilistic Modelling for Four-Tops at the LHC
• Beyond Cuts in Small Signal Scenarios -- Enhanced Sneutrino Detectability Using Machine Learning
• A Final Word on FCNC-Baryogenesis from Two Higgs Doublets
• Climbing to the Top of the ATLAS 13 TeV data
• Correlating the CDF $W$-boson mass shift with the $b\to s{\ell }^{+}{\ell }^{-}$ anomalies
• Les Houches 2023 -- Physics at TeV Colliders: Report on the Standard Model Precision Wishlist
• Search for top-philic heavy resonances in $pp$ collisions at $\sqrt{s}=13$ TeV with the ATLAS detector
• The Hierarchy Problem and the Top Yukawa: An Alternative to Top Partner Solutions
• Prospect and implications of $cg\to b{H}^{+}\to bA{W}^{+}$ production at the LHC
• Attention to the strengths of physical interactions: Transformer and graph-based event classification for particle physics experiments
• Mutually elusive: vectorlike antileptons and leptoquarks
• Combination and summary of ATLAS dark matter searches interpreted in a 2HDM with a pseudo-scalar mediator using 139 fb${}^{-1}$ of $\sqrt{s}=13$ TeV $pp$ collision data
• Search for leptoquark pair production decaying into $t{e}^{-}\bar{t}{e}^{+}$ or $t{\mu }^{-}\bar{t}{\mu }^{+}$ in multi-lepton final states in $pp$ collisions at 13 TeV with the ATLAS detector
• Boosting Beyond: A Novel Approach to Probing Top-Philic Resonances at the LHC
• Generic tests of CP-violation in high-$p_{\text{T}}$ multi-lepton signals at the LHC and beyond
• Search for $t\bar{t}H/A\to t\bar{t}t\bar{t}$ production in proton-proton collisions at $\sqrt{s}=13$ TeV with the ATLAS detector
• Hadroproduction of four top quarks in the POWHEG BOX
• Search for heavy neutral leptons in decays of W bosons produced in 13 TeV pp collisions using prompt signatures in the ATLAS detector
• Searches for new interactions within the SMEFT framework at present and future colliders
• Boosted and semi-boosted all-hadronic $t\bar{t}$ reconstruction performance on kinematic variables for selected BSM models using a 2D extesion of the BumpHunter algorithm