In:
The European Physical Journal C, Springer Science and Business Media LLC, Vol. 80, No. 2 ( 2020-02)
Abstract:
The standard model (SM) production of four top quarks ( $$\text {t} {}{\overline{\text {t}}} \text {t} {}{\overline{\text {t}}} $$ t t ¯ t t ¯ ) 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 $$\,\text {fb}^{-1}$$ fb - 1 at a center-of-mass energy of 13 $$\,\text {TeV}$$ TeV . 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 $$\text {t} {}{\overline{\text {t}}} \text {t} {}{\overline{\text {t}}} $$ t t ¯ t t ¯ signal are respectively 2.6 and 2.7 standard deviations, and the $$\text {t} {}{\overline{\text {t}}} \text {t} {}{\overline{\text {t}}} $$ t t ¯ t t ¯ cross section is measured to be $$12.6^{+5.8}_{-5.2}\,\text {fb} $$ 12 . 6 - 5.2 + 5.8 fb . The results are used to constrain the Yukawa coupling of the top quark to the Higgs boson, $$y_{\text {t}}$$ y t , yielding a limit of $$|y_{\text {t}}/y_{\text {t}}^{\mathrm {SM}} | 〈 1.7$$ | y t / y t SM | 〈 1.7 at $$95\%$$ 95 % confidence level, where $$y_{\text {t}}^{\mathrm {SM}}$$ y t SM is the SM value of $$y_{\text {t}}$$ y t . They are also used to constrain the oblique parameter of the Higgs boson in an effective field theory framework, $$\hat{H} 〈 0.12$$ H ^ 〈 0.12 . 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 $$\,\text {GeV}$$ GeV and 350–550 $$\,\text {GeV}$$ GeV for scalar and pseudoscalar bosons, respectively. Upper bounds are also set on couplings of the top quark to new light particles.
Type of Medium:
Online Resource
ISSN:
1434-6044
,
1434-6052
DOI:
10.1140/epjc/s10052-019-7593-7
Language:
English
Publisher:
Springer Science and Business Media LLC
Publication Date:
2020
detail.hit.zdb_id:
1397769-6
detail.hit.zdb_id:
1459069-4
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