Search for a new Z′ gauge boson in 4μ events with the ATLAS experiment
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jats:titleAjats:scbstract</jats:sc> </jats:title>jats:pThis paper presents a search for a new jats:italicZ</jats:italic>′ vector gauge boson with the ATLAS experiment at the Large Hadron Collider using jats:italicpp</jats:italic> collision data collected at jats:inline-formulajats:alternativesjats:tex-math$$ \sqrt{s} $$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> mml:msqrt mml:mis</mml:mi> </mml:msqrt> </mml:math></jats:alternatives></jats:inline-formula> = 13 TeV, corresponding to an integrated luminosity of 139 fbjats:supjats:italic−</jats:italic>1</jats:sup>. The new gauge boson jats:italicZ</jats:italic>′ is predicted by jats:italicL</jats:italic>jats:subjats:italicμ</jats:italic></jats:sub> − jats:italicL</jats:italic>jats:subjats:italicτ</jats:italic></jats:sub> models to address observed phenomena that can not be explained by the Standard Model. The search examines the four-muon (4jats:italicμ</jats:italic>) final state, using a deep learning neural network classifier to separate the jats:italicZ</jats:italic>′ signal from the Standard Model background events. The di-muon invariant masses in the 4jats:italicμ</jats:italic> events are used to extract the jats:italicZ</jats:italic>′ resonance signature. No significant excess of events is observed over the predicted background. Upper limits at a 95% confidence level on the jats:italicZ</jats:italic>′ production cross-section times the decay branching fraction of jats:italicpp → Z</jats:italic>′jats:italicμμ →</jats:italic> 4jats:italicμ</jats:italic> are set from 0.31 to 4.3 fb for the jats:italicZ</jats:italic>′ mass ranging from 5 to 81 GeV. The corresponding common coupling strengths, jats:italicg</jats:italic>jats:subjats:italicZ</jats:italic>′</jats:sub>, of the jats:italicZ</jats:italic>′ boson to the second and third generation leptons above 0.003 – 0.2 have been excluded.</jats:p>
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Acknowledgements: We thank CERN for the very successful operation of the LHC, as well as the support staff from our institutions without whom ATLAS could not be operated efficiently. We acknowledge the support of ANPCyT, Argentina; YerPhI, Armenia; ARC, Australia; BMWFW and FWF, Austria; ANAS, Azerbaijan; CNPq and FAPESP, Brazil; NSERC, NRC and CFI, Canada; CERN; ANID, Chile; CAS, MOST and NSFC, China; Minciencias, Colombia; MEYS CR, Czech Republic; DNRF and DNSRC, Denmark; IN2P3-CNRS and CEA-DRF/IRFU, France; SRNSFG, Georgia; BMBF, HGF and MPG, Germany; GSRI, Greece; RGC and Hong Kong SAR, China; ISF and Benoziyo Center, Israel; INFN, Italy; MEXT and JSPS, Japan; CNRST, Morocco; NWO, Netherlands; RCN, Norway; MEiN, Poland; FCT, Portugal; MNE/IFA, Romania; MESTD, Serbia; MSSR, Slovakia; ARRS and MIZŠ, Slovenia; DSI/NRF, South Africa; MICINN, Spain; SRC and Wallenberg Foundation, Sweden; SERI, SNSF and Cantons of Bern and Geneva, Switzerland; MOST, Taiwan; TENMAK, Türkiye; STFC, United Kingdom; DOE and NSF, United States of America. In addition, individual groups and members have received support from BCKDF, CANARIE, Compute Canada and CRC, Canada; PRIMUS 21/SCI/017 and UNCE SCI/013, Czech Republic; COST, ERC, ERDF, Horizon 2020 and Marie Skłodowska-Curie Actions, European Union; Investissements d’Avenir Labex, Investissements d’Avenir Idex and ANR, France; DFG and AvH Foundation, Germany; Herakleitos, Thales and Aristeia programmes co-financed by EU-ESF and the Greek NSRF, Greece; BSF-NSF and MINERVA, Israel; Norwegian Financial Mechanism 2014–2021, Norway; NCN and NAWA, Poland; La Caixa Banking Foundation, CERCA Programme Generalitat de Catalunya and PROMETEO and GenT Programmes Generalitat Valenciana, Spain; Göran Gustafssons Stiftelse, Sweden; The Royal Society and Leverhulme Trust, United Kingdom. The crucial computing support from all WLCG partners is acknowledged gratefully, in particular from CERN, the ATLAS Tier-1 facilities at TRIUMF (Canada), NDGF (Denmark, Norway, Sweden), CC-IN2P3 (France), KIT/GridKA (Germany), INFN-CNAF (Italy), NL-T1 (Netherlands), PIC (Spain), ASGC (Taiwan), RAL (U.K.) and BNL (U.S.A.), the Tier-2 facilities worldwide and large non-WLCG resource providers. Major contributors of computing resources are listed in ref. [79].
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1029-8479
