Search for pair production of third-generation leptoquarks decaying into a bottom quark and a $\ddot{I}„$-lepton with the ATLAS detector

Abstract

A search for pair-produced scalar or vector leptoquarks decaying into a $b$-quark and a $\ddot{I}„$-lepton is presented using the full LHC Run 2 (2015-2018) data sample of 139 fb${}^{-1}$ collected with the ATLAS detector in proton-proton collisions at a centre-of-mass energy of $\sqrt{s}=13$ TeV. Events in which at least one $\ddot{I}„$-lepton decays hadronically are considered, and multivariate discriminants are used to extract the signals. No significant deviations from the Standard Model expectation are observed and 95% confidence-level upper limits on the production cross-section are derived as a function of leptoquark mass and branching ratio $B$ into a $\ddot{I}„$-lepton and $b$-quark. For scalar leptoquarks, masses below 1460 GeV are excluded assuming $B=100$%, while for vector leptoquarks the corresponding limit is 1650 GeV (1910 GeV) in the minimal-coupling (Yang-Mills) scenario.

51 pages in total, author list starting page 34, 10 figures, 5 tables, published in EPJC. All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/EXOT-2021-15