Search for production of four top quarks in final states with same-sign or multiple leptons in proton-proton collisions at [Formula omitted][Formula omitted]

• Published in: The European physical journal. C, Particles and fields Vol. 80; no. 2
• Main Authors: Sirunyan, A. M, Tumasyan, A, Adam, W, Ambrogi, F, Bergauer, T, Brandstetter, J, Dragicevic, M
• Format: Journal Article
• Language: English
• Published: Springer 31.01.2020
• Subjects: Analysis; Collisions (Nuclear physics); Nuclear energy; Quarks
• ISSN: 1434-6044; 1434-6052
• DOI: 10.1140/epjc/s10052-019-7593-7

The standard model (SM) production of four top quarks ( [Formula omitted]) in proton-proton collisions is studied by the CMS Collaboration. The data sample, collected during the 2016-2018 data taking of the LHC, corresponds to an integrated luminosity of 137 [Formula omitted] at a center-of-mass energy of 13 [Formula omitted]. The events are required to contain two same-sign charged leptons (electrons or muons) or at least three leptons, and jets. The observed and expected significances for the [Formula omitted] signal are respectively 2.6 and 2.7 standard deviations, and the [Formula omitted] cross section is measured to be [Formula omitted]. The results are used to constrain the Yukawa coupling of the top quark to the Higgs boson, [Formula omitted], yielding a limit of [Formula omitted] at [Formula omitted] confidence level, where [Formula omitted] is the SM value of [Formula omitted]. They are also used to constrain the oblique parameter of the Higgs boson in an effective field theory framework, [Formula omitted]. Limits are set on the production of a heavy scalar or pseudoscalar boson in Type-II two-Higgs-doublet and simplified dark matter models, with exclusion limits reaching 350-470 [Formula omitted] and 350-550 [Formula omitted] for scalar and pseudoscalar bosons, respectively. Upper bounds are also set on couplings of the top quark to new light particles.