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

Abstract

A search for pair production of third-generation scalar leptoquarks decaying into a top quark and a $\tau$-lepton is presented. The search is based on a dataset of $pp$ collisions at $\sqrt{s}=13$ TeV recorded with the ATLAS detector during Run 2 of the Large Hadron Collider, corresponding to an integrated luminosity of 139 fb${}^{-1}$. Events are selected if they have one light lepton (electron or muon) and at least one hadronically decaying $\tau$-lepton, or at least two light leptons. In addition, two or more jets, at least one of which must be identified as containing $b$-hadrons, are required. Six final states, defined by the multiplicity and flavour of lepton candidates, are considered in the analysis. Each of them is split into multiple event categories to simultaneously search for the signal and constrain several leading backgrounds. The signal-rich event categories require at least one hadronically decaying $\tau$-lepton candidate and exploit the presence of energetic final-state objects, which is characteristic of signal events. No significant excess above the Standard Model expectation is observed in any of the considered event categories, and 95% CL upper limits are set on the production cross section as a function of the leptoquark mass, for different assumptions about the branching fractions into $t\tau$ and $b\nu$. Scalar leptoquarks decaying exclusively into $t\tau$ are excluded up to masses of 1.43 TeV while, for a branching fraction of 50% into $t\tau$, the lower mass limit is 1.22 TeV.

arXiv comment59 pages in total, author list starting page 43, 15 figures, 10 tables, submitted to JHEP. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/EXOT-2019-15/

References in corpus (90)

• 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
• Asymptotic formulae for likelihood-based tests of new physics
• A general framework for implementing NLO calculations in shower Monte Carlo programs: the POWHEG BOX
• A New Method for Combining NLO QCD with Shower Monte Carlo Algorithms
• Matching NLO QCD computations with Parton Shower simulations: the POWHEG method
• Parton distributions for the LHC Run II
• Event generation with SHERPA 1.1
• Herwig++ Physics and Manual
• High-Energy-Physics Event Generation with PYTHIA 6.1
• Parton distributions with LHC data
• The ATLAS Simulation Infrastructure
• Confidence Level Computation for Combining Searches with Small Statistics
• PDF4LHC recommendations for LHC Run II
• Parton distributions in the LHC era: MMHT 2014 PDFs
• HDECAY: a Program for Higgs Boson Decays in the Standard Model and its Supersymmetric Extension
• The total top quark pair production cross-section at hadron colliders through O(alpha_S^4)
• Scattering Amplitudes with Open Loops
• Top++: a program for the calculation of the top-pair cross-section at hadron colliders
• Herwig 7.0 / Herwig++ 3.0 Release Note
• A parton shower algorithm based on Catani-Seymour dipole factorisation
• A Positive-Weight Next-to-Leading-Order Monte Carlo for Heavy Flavour Hadroproduction
• Comix, a new matrix element generator
• PHOTOS Monte Carlo: a precision tool for QED corrections in Z and W decays
• Tuning Monte Carlo Generators: The Perugia Tunes
• QCD matrix elements + parton showers: The NLO case
• Performance of the ATLAS Trigger System in 2015
• Single-top Wt-channel production matched with parton showers using the POWHEG method
• Two-loop soft anomalous dimensions for single top quark associated production with a W- or H-
• Automatic spin-entangled decays of heavy resonances in Monte Carlo simulations
• The Catchment Area of Jets
• Percent level precision physics at the Tevatron: first genuine NNLO QCD corrections to q qbar -> t tbar + X
• Top-pair production at hadron colliders with next-to-next-to-leading logarithmic soft-gluon resummation
• Muon reconstruction performance of the ATLAS detector in proton--proton collision data at $\sqrt{s}$=13 TeV
• NNLO corrections to top-pair production at hadron colliders: the all-fermionic scattering channels
• NLO single-top production matched with shower in POWHEG: s- and t-channel contributions
• NNLO corrections to top pair production at hadron colliders: the quark-gluon reaction
• Production and Integration of the ATLAS Insertable B-Layer
• 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
• Performance of pile-up mitigation techniques for jets in $pp$ collisions at $\sqrt{s}=8$ TeV using the ATLAS detector
• Improved luminosity determination in pp collisions at sqrt(s) = 7 TeV using the ATLAS detector at the LHC
• Electron and photon performance measurements with the ATLAS detector using the 2015-2017 LHC proton-proton collision data
• B-physics anomalies: a guide to combined explanations
• One Leptoquark to Rule Them All: A Minimal Explanation for $R_{D^{(\ast )}}$, $R_K$ and $(g-2{)}_{\mu }$
• Stop Production at Hadron Colliders
• Higgs Radiation off Top Quarks at the Tevatron and the LHC
• NLO QCD corrections to t anti-t H production in hadron collisions
• 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
• Performance of electron and photon triggers in ATLAS during LHC Run 2
• Performance of missing transverse momentum reconstruction with the ATLAS detector using proton-proton collisions at $\sqrt{s}$ = 13 TeV
• Jet energy scale and resolution measured in proton-proton collisions at $\sqrt{s}=13$ TeV with the ATLAS detector
• Performance of the ATLAS muon triggers in Run 2
• $R_K$ and future $b\to s\ell \ell$ BSM opportunities
• Associated Higgs production with top quarks at the Large Hadron Collider: NLO QCD corrections
• Flavor models for $\bar{B}\to D^{(\ast )}\tau \bar{\nu }$
• Higgs boson production in association with top quarks in the POWHEG BOX
• Supersymmetric top and bottom squark production at hadron colliders
• Electron reconstruction and identification in the ATLAS experiment using the 2015 and 2016 LHC proton-proton collision data at $\sqrt{s}$ = 13 TeV
• Single-top production in MC@NLO
• QCD NLO and EW NLO corrections to $t\bar{t}H$ production with top quark decays at hadron collider
• Pair production of scalar leptoquarks at the LHC
• Associated Top Quark-Higgs Boson Production at the LHC
• Pair production of scalar leptoquarks at the Tevatron
• NNLL-fast: predictions for coloured supersymmetric particle production at the LHC with threshold and Coulomb resummation
• What is the scale of new physics behind the $B$-flavour anomalies?
• Evidence for the associated production of the Higgs boson and a top quark pair with the ATLAS detector
• Weak corrections to Higgs hadroproduction in association with a top-quark pair
• Identification and energy calibration of hadronically decaying tau leptons with the ATLAS experiment in $pp$ collisions at $\sqrt{s}$=8 TeV
• Measurement of the photon identification efficiencies with the ATLAS detector using LHC Run 2 data collected in 2015 and 2016
• Measurement of the $t\bar{t}Z$ and $t\bar{t}W$ cross sections in proton-proton collisions at $\sqrt{s}=13$ TeV with the ATLAS detector
• Search for pairs of scalar leptoquarks decaying into quarks and electrons or muons in $\sqrt{s}=13$ TeV pp collisions with the ATLAS detector
• Measurements of top-quark pair differential and double-differential cross-sections in the $\ell$+jets channel with $pp$ collisions at $\sqrt{s}=13$ TeV using the ATLAS detector
• Pair Production of Scalar Leptoquarks at the LHC to NLO Parton Shower Accuracy
• NNLL resummation for stop pair-production at the LHC
• 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
• Leptoquark Single and Pair production at LHC with CalcHEP/CompHEP in the complete model
• Precision predictions for scalar leptoquark pair-production at hadron colliders
• Four-point correlation function of stress-energy tensors in N=4 superconformal theories
• Search for heavy neutrinos and third-generation leptoquarks in hadronic states of two $\tau$ leptons and two jets in proton-proton collisions at $\sqrt{s}=$ 13 TeV
• $B$ decay anomalies and dark matter from vectorlike confinement
• Searches for third-generation scalar leptoquarks in $\sqrt{s}$ = 13 TeV pp collisions with the ATLAS detector
• Constraints on models of scalar and vector leptoquarks decaying to a quark and a neutrino at $\sqrt{s}=$ 13 TeV
• Search for third-generation scalar leptoquarks decaying to a top quark and a $\tau$ lepton at $\sqrt{s}=$ 13 TeV
• Search for leptoquarks coupled to third-generation quarks in proton-proton collisions at $\sqrt{s}=$ 13 TeV
• Search for a singly produced third-generation scalar leptoquark decaying to a $\tau$ lepton and a bottom quark in proton-proton collisions at $\sqrt{s}=$ 13 TeV
• Search for pair production of scalar leptoquarks decaying into first- or second-generation leptons and top quarks in proton-proton collisions at $\sqrt{s}$ = 13 TeV with the ATLAS detector

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• Leptoquark-vectorlike quark model for the CDF $m_W$, $(g-2{)}_{\mu }$, $R_{K^{(\ast )}}$ anomalies and neutrino mass
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• Constraints on leptoquarks from lepton-flavour-violating tau-lepton processes
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• Collider Signatures of a Scalar Leptoquark and Vector-like Lepton in Light of Muon Anomaly
• Leptoquark and vector-like quark extended models as the explanation of the muon $g-2$ anomaly
• Leptoquarks, axions and the unification of B, L, and Peccei-Quinn symmetries
• Gravitational wave signals from leptoquark-induced first order electroweak phase transitions
• Leptonic signatures of color-sextet scalars
• Mutually elusive: vectorlike antileptons and leptoquarks
• 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
• Search for scalar leptoquarks produced via $\tau$-lepton-quark scattering in pp collisions at $\sqrt{s}$ = 13 TeV
• A search for $R$-parity violating supersymmetric decays of the top squark to a $b$-jet and a lepton in $\sqrt{s}$ = 13 TeV $pp$ collisions with the ATLAS detector
• Constraining electroweak and strongly charged long-lived particles with CheckMATE
• Phenomenological study of a gauged $L_{\mu }-L_{\tau }$ model with a scalar leptoquark
• Constraining the new contributions to electron $g-2$ in a radiative neutrino mass model
• Constraining Scalar Doublet and Triplet Leptoquarks with Vacuum Stability and Perturbativity