Abstract
A search optimized for new heavy particles decaying to two b-quarks and produced in association with additional b-quarks is reported. The sensitivity is improved by b-tagging at least one lower-pT jet in addition to the two highest-pT jets. The data used in this search correspond to an integrated luminosity of 103 fb−1 collected with a dedicated trijet trigger during the 2017 and 2018 s=13 TeV proton-proton collision runs with the ATLAS detector at the LHC. The search looks for resonant peaks in the b-tagged dijet invariant mass spectrum over a smoothly falling background. The background is estimated with an innovative data-driven method based on orthonormal functions. The observed b-tagged dijet invariant mass spectrum is compatible with the background-only hypothesis. Upper limits at 95% confidence level on a heavy vector-boson production cross section times branching ratio to a pair of b-quarks are derived.Received 23 August 2021Accepted 11 November 2021DOI:https://doi.org/10.1103/PhysRevD.105.012001Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.© 2022 CERN, for the ATLAS CollaborationPhysics Subject Headings (PhySH)Research AreasExtensions of Higgs sectorExtensions of gauge sectorParticles & Fields
Highlights
New particles beyond the Standard Model with preferential couplings to third-generation quarks are predicted by many models [1,2,3,4,5,6] and have been extensively searched for by experiments at the Tevatron and the LHC
The phenomenological work in Refs. [18,19] predicts new heavy vector bosons, a Z0 boson and W0 boson, mainly coupled to third-generation leptons and quarks. This model offers an explanation for the lepton-flavor universality (LFU) anomalies, and predicts Z0 boson production in association with thirdgeneration quarks via gluon splitting in the LHC experiments, due to the vanishingly small b-quark and top-quark parton distribution functions (PDFs) for protons at the TeV scale
The BumpHunter algorithm is adopted to quantify the statistical significance of any localized excess in the binned mjj distribution
Summary
New particles beyond the Standard Model with preferential couplings to third-generation quarks are predicted by many models [1,2,3,4,5,6] and have been extensively searched for by experiments at the Tevatron and the LHC. [18,19] predicts new heavy vector bosons, a Z0 boson and W0 boson, mainly coupled to third-generation leptons and quarks This model offers an explanation for the LFU anomalies, and predicts Z0 boson production in association with thirdgeneration quarks via gluon splitting in the LHC experiments, due to the vanishingly small b-quark and top-quark parton distribution functions (PDFs) for protons at the TeV scale. The b-tagging criterion for the third and fourth jets increases the sensitivity by 20%–50% at a mass scale of 1.3 –3 TeV. This is the first search probing the mass region up to 3.6 TeV in this final state. The model proposed in Refs. [18,19] is compared with data for the first time
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