Search for pair-produced scalar and vector leptoquarks decaying into third-generation quarks and first- or second-generation leptons in pp collisions with the ATLAS detector

Abstract

A search for pair-produced scalar and vector leptoquarks decaying into quarks and leptons of different generations is presented. It uses the full LHC Run 2 (2015-2018) data set of 139 fb${}^{-1}$ collected with the ATLAS detector in proton-proton collisions at a centre-of-mass energy of $\sqrt{s}=13$ TeV. Scalar leptoquarks with charge -(1/3)e as well as scalar and vector leptoquarks with charge +(2/3)e are considered. All possible decays of the pair-produced leptoquarks into quarks of the third generation (t, b) and charged or neutral leptons of the first or second generation ($e,\mu ,\nu$) with exactly one electron or muon in the final state are investigated. No significant deviations from the Standard Model expectation are observed. Upper limits on the production cross-section are provided for eight models as a function of the leptoquark mass and the branching ratio of the leptoquark into the charged or neutral lepton. In addition, lower limits on the leptoquark masses are derived for all models across a range of branching ratios. Two of these models have the goal of providing an explanation for the recent B-anomalies. In both models, a vector leptoquark decays into charged and neutral leptons of the second generation with a similar branching fraction. Lower limits of 1980 GeV and 1710 GeV are set on the leptoquark mass for these two models.

arXiv comment46 pages in total, author list starting at page 31, 10 figures, 5 tables, submitted to JHEP. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/EXOT-2019-12/

References in corpus (46)

• 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
• An Introduction to PYTHIA 8.2
• 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
• Parton distributions with LHC data
• PDF4LHC recommendations for LHC Run II
• Scattering Amplitudes with Open Loops
• Top++: a program for the calculation of the top-pair cross-section at hadron colliders
• A parton shower algorithm based on Catani-Seymour dipole factorisation
• A Positive-Weight Next-to-Leading-Order Monte Carlo for Heavy Flavour Hadroproduction
• QCD Matrix Elements + Parton Showers
• Comix, a new matrix element generator
• Event Generation with Sherpa 2.2
• QCD matrix elements + parton showers: The NLO case
• High-precision QCD at hadron colliders: electroweak gauge boson rapidity distributions at NNLO
• Measuring masses of semi-invisibly decaying particles pair produced at hadron colliders
• Single-top Wt-channel production matched with parton showers using the POWHEG method
• QCD matrix elements and truncated showers
• Collier: a fortran-based Complex One-Loop LIbrary in Extended Regularizations
• Automatic spin-entangled decays of heavy resonances in Monte Carlo simulations
• Single-top hadroproduction in association with a W boson
• A critical appraisal of NLO+PS matching methods
• B-physics anomalies: a guide to combined explanations
• Stop Production at Hadron Colliders
• Anomalies in $B$-decays and $U(2)$ flavour symmetry
• $R_K$ and future $b\to s\ell \ell$ BSM opportunities
• Supersymmetric top and bottom squark production at hadron colliders
• Pair production of scalar leptoquarks 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?
• Stop the Top Background of the Stop Search
• Transverse masses and kinematic constraints: from the boundary to the crease
• High-pT Signatures in Vector-Leptoquark Models
• $(g-2{)}_{\mu }$, Lepton Flavour Violation and $Z$ Decays with Leptoquarks: Correlations and Future Prospects
• A nonsupersymmetric resolution of the anomalous muon magnetic moment
• Pair Production of Scalar Leptoquarks at the LHC to NLO Parton Shower Accuracy
• NNLL resummation for stop pair-production at the LHC
• Precision predictions for scalar leptoquark pair-production at hadron colliders
• $B$ decay anomalies and dark matter from vectorlike confinement

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• Les Houches guide to reusable ML models in LHC analyses
• Search for pair production of scalar and vector leptoquarks decaying to muons and bottom quarks in proton-proton collisions at $\sqrt{s}$ = 13 TeV
• 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
• 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
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• Constraining the new contributions to electron $g-2$ in a radiative neutrino mass model