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

The CMS collaboration
Phys.Lett.B 844 (2023) 138076, 2023.

Abstract
The production of four top quarks ($\mathrm{t\bar{t}t\bar{t}}$) 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 $\mathrm{t\bar{t}t\bar{t}}$ measurement that includes the all-hadronic final state. The observed significance of the $\mathrm{t\bar{t}t\bar{t}}$ signal in these final states of 3.9 standard deviations (1.5 expected) provides evidence for $\mathrm{t\bar{t}t\bar{t}}$ production, with a measured cross section of 36 $^{+12}_{-11}$ 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.

  • Figure 2

    Data from Figure 2.

    10.17182/hepdata.135833.v1/t1

    The jet multiplicity for $N_\textrm{b} \ge 4$ in the opposite-sign dilepton channel for the combined 2017--2018 dataset with dilepton decay...

  • Figure 3

    Data from Figure 3.

    10.17182/hepdata.135833.v1/t2

    The distribution of the BDT discriminants for the 2016--2018 data set for three different categories in the combined single-electron and...

  • Figure 5a

    Data from Figure 5 (left).

    10.17182/hepdata.135833.v1/t3

    The distribution of the BDT discriminants for the full 2016--2018 data set in the all-hadronic channel. The SR category shown...

  • Figure 5b

    Data from Figure 5 (right).

    10.17182/hepdata.135833.v1/t4

    The distribution of the BDT discriminants for the full 2016--2018 data set in the all-hadronic channel. The SR category shown...

  • Figure 6

    Data from Figure 6.

    10.17182/hepdata.135833.v1/t5

    Expected and observed significance (in standard deviations) for $\textrm{t}\bar{\textrm{t}}\textrm{t}\bar{\textrm{t}}$ production from each final state and the combination with previous CMS...

  • Table 1

    Data from Table 1.

    10.17182/hepdata.135833.v1/t6

    Measured signal strength ($\mu = \sigma_{\textrm{t}\bar{\textrm{t}}\textrm{t}\bar{\textrm{t}}}/ \sigma_{\textrm{t}\bar{\textrm{t}}\textrm{t}\bar{\textrm{t}}} ^{\textrm{SM}}$), corresponding cross section (in fb), and the expected and observed significance (in...

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