Search for standard model production of four top quarks in proton–proton collisions at
Author(s)
CMS Collaboration; Abercrombie, Daniel Robert; Allen, Brandon Leigh; Apyan, Aram; Azzolini, Virginia; Barbieri, Richard Alexander; Baty, Austin Alan; Bi, Ran; Bierwagen, Katharina; Brandt, Stephanie Akemi; Busza, Wit; Cali, Ivan Amos; D'Alfonso, Mariarosaria; Demiragli, Zeynep; Di Matteo, Leonardo; Gomez-Ceballos, Guillelmo; Goncharov, Maxim; Hsu, Dylan George; Iiyama, Yutaro; Innocenti, Gian Michele; Klute, Markus; Kovalskyi, Dmytro; Krajczar, Krisztian F.; Lai, Yue Shi; Lee, Yen-Jie; Levin, Amy Elizabeth; Luckey Jr, P David; Maier, Benedikt; Marini, Andrea Carlo; McGinn, Christopher Francis; Mironov, Camelia Maria; Narayanan, Siddharth Madhavan; Niu, Xinmei; Paus, Christoph M. E.; Roland, Christof E; Roland, Gunther M; Salfeld-Nebgen, Jakob Maxillian Henry; Stephans, George S. F.; Tatar, Kaya; Varma, Mukund Madhav; Velicanu, Dragos Alexandru; Veverka, Jan; Wang, Jing; Wang, Ta-Wei; Wyslouch, Boleslaw; Yang, Ming; ... Show more Show less
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A search for events containing four top quarks (tt¯tt¯) is reported from proton–proton collisions recorded by the CMS experiment at √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 tt¯tt¯ and tt¯ 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 tt¯tt¯ 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 tt¯tt¯ production to date. Keywords: CMS; Physics; Top; BSM
Date issued
2017-06Department
Massachusetts Institute of Technology. Department of Nuclear Science and Engineering; Massachusetts Institute of Technology. Department of Physics; Massachusetts Institute of Technology. Laboratory for Nuclear ScienceJournal
Physics Letters B
Publisher
Elsevier
Citation
Sirunyan, A.M. et al. “Search for Standard Model Production of Four Top Quarks in Proton–proton Collisions At √s = 13 TeV.” Physics Letters B 772 (September 2017): 336–358 © 2017 The Author(s)
Version: Final published version
ISSN
0370-2693