Evidence for four-top quark production in proton-proton collisions at $\sqrt{s}$ = 13 TeV

Abstract

The production of four top quarks ($\mathrm{t}\bar{\mathrm{t}}\mathrm{t}\bar{\mathrm{t}}$) is studied with LHC proton-proton collision data samples collected by the CMS experiment at a center-of-mass energy of 13 TeV, and corresponding to integrated luminosities of up to 138 fb${}^{-1}$. Events that have no leptons (all-hadronic), one lepton, or two opposite-sign leptons (where lepton refers only to prompt electrons or prompt muons) are considered. This is the first $\mathrm{t}\bar{\mathrm{t}}\mathrm{t}\bar{\mathrm{t}}$ measurement that includes the all-hadronic final state. The observed significance of the $\mathrm{t}\bar{\mathrm{t}}\mathrm{t}\bar{\mathrm{t}}$ signal in these final states of 3.9 standard deviations (1.5 expected) provides evidence for $\mathrm{t}\bar{\mathrm{t}}\mathrm{t}\bar{\mathrm{t}}$ production, with a measured cross section of 36 ${}_{-11}^{+12}$ fb. Combined with earlier CMS results in other final states, the signal significance is 4.0 standard deviations (3.2 expected). The combination returns an observed cross section of 17 $\pm$ 4 (stat) $\pm$ 3 (syst) fb, which is consistent with the standard model prediction.

Replaced with the published version. Added the journal reference and the DOI. All the figures and tables, including additional supplementary figures and tables, can be found at http://cms-results.web.cern.ch/cms-results/public-results/publications/TOP-21-005 (CMS Public Pages)

References in corpus (6)

• The automated computation of tree-level and next-to-leading order differential cross sections, and their matching to parton shower simulations
• An Introduction to PYTHIA 8.2
• Comparative study of various algorithms for the merging of parton showers and matrix elements in hadronic collisions
• Particle-flow reconstruction and global event description with the CMS detector
• Jet energy scale and resolution in the CMS experiment in pp collisions at 8 TeV
• Pileup Per Particle Identification

Cited by in corpus (5)

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• TOP2024: an overview of experimental results
• Machine learning in top quark physics at ATLAS and CMS