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Search for standard model production of four top quarks in proton-proton collisions at $\sqrt{s} = 13$ TeV


Abstract

A search for events containing four top quarks ($t\overline tt\overline t$) is reported from proton–proton collisions recorded by the CMS experiment at $\sqrt{s} = 13$ TeV and corresponding to an integrated luminosity of 2.6 $fb^{−1}$. The analysis considers the single-lepton (e or μ)+jets and the opposite-sign dilepton ($μ^+μ^−, μ^±e^∓$, or $e^+e^−)$+jets channels. It uses boosted decision trees to combine information on the global event and jet properties to distinguish between ($t\overline tt\overline t$) and $t\overline t$ production. The number of events observed after all selection requirements is consistent with expectations from background and standard model signal predictions, and an upper limit is set on the cross section for ($t\overline tt\overline t$) production in the standard model of 94 fb at 95% confidence level (10.2× the prediction), with an expected limit of 118 fb. This is combined with the results from the published CMS search in the same-sign dilepton channel, resulting in an improved limit of 69 fb at 95% confidence level (7.4× the prediction), with an expected limit of 71 fb. These are the strongest constraints on the rate of ($t\overline tt\overline t$) production to date.

Abstract

A search for events containing four top quarks ($t\overline tt\overline t$) is reported from proton–proton collisions recorded by the CMS experiment at $\sqrt{s} = 13$ TeV and corresponding to an integrated luminosity of 2.6 $fb^{−1}$. The analysis considers the single-lepton (e or μ)+jets and the opposite-sign dilepton ($μ^+μ^−, μ^±e^∓$, or $e^+e^−)$+jets channels. It uses boosted decision trees to combine information on the global event and jet properties to distinguish between ($t\overline tt\overline t$) and $t\overline t$ production. The number of events observed after all selection requirements is consistent with expectations from background and standard model signal predictions, and an upper limit is set on the cross section for ($t\overline tt\overline t$) production in the standard model of 94 fb at 95% confidence level (10.2× the prediction), with an expected limit of 118 fb. This is combined with the results from the published CMS search in the same-sign dilepton channel, resulting in an improved limit of 69 fb at 95% confidence level (7.4× the prediction), with an expected limit of 71 fb. These are the strongest constraints on the rate of ($t\overline tt\overline t$) production to date.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Physics Institute
Dewey Decimal Classification:530 Physics
Language:English
Date:2017
Deposited On:18 Dec 2017 09:40
Last Modified:18 Dec 2017 15:56
Publisher:Elsevier
ISSN:0370-2693
Free access at:Publisher DOI. An embargo period may apply.
Publisher DOI:https://doi.org/10.1016/j.physletb.2017.06.064

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