The distribution of the BDT discriminants for the full 2016--2018 data set in the all-hadronic channel. The sample VR category shown is defined by $N_\textrm{RT} \geq 2$, $H_T > 1100$ GeV. The background from QCD multijet and $\textrm{t}\bar{\textrm{t}}$ production is derived from control regions in the data. Estimates for the $\textrm{t}\bar{\textrm{t}}\textrm{t}\bar{\textrm{t}}$ signal and other backgrounds are shown using simulated samples. The hatched bands correspond to the estimated total uncertainty.

The distribution of the BDT discriminants for the full 2016--2018 data set in the all-hadronic channel. The SR category shown in this figure is defined by $N_\textrm{RT}=1$, $N_\textrm{BT} \geq 1$, $H_T > 1400$ GeV. The background from QCD multijet and $\textrm{t}\bar{\textrm{t}}$ production is derived from control regions in the data. Estimates for the $\textrm{t}\bar{\textrm{t}}\textrm{t}\bar{\textrm{t}}$ signal and other backgrounds are shown using simulated samples. The hatched bands correspond to the estimated total uncertainty after the fit.

The distribution of the BDT discriminants for the full 2016--2018 data set in the all-hadronic channel. The SR category shown in this figure is defined by $N_\textrm{RT} = 2$, $H_T > 1100$ GeV. The background from QCD multijet and $\textrm{t}\bar{\textrm{t}}$ production is derived from control regions in the data. Estimates for the $\textrm{t}\bar{\textrm{t}}\textrm{t}\bar{\textrm{t}}$ signal and other backgrounds are shown using simulated samples. The hatched bands correspond to the estimated total uncertainty after the fit.

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 results (EPJC 80 (2020) 75 and JHEP 11 (2019) 082). The same-sign dilepton and multilepton (SSDL\&ML) final state results are from EPJC 80 (2020) 75.

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 standard deviations) for $\textrm{t}\bar{\textrm{t}}\textrm{t}\bar{\textrm{t}}$ production from all analysis channels. This table shows production from each analysis channel in this Letter, the combination of those channels, the results from previously published results, and the full combination of all CMS 2016-2018 results.

Distributions of $\Delta\phi$ as obtained from simulation, requiring various $\textrm{t}$ tag multiplicities for the signal in two representative combinations of (gluino, neutralino) masses with large (2.2, 0.1)$\mathrm{TeV}$ and small (1.8, 1.3)$\mathrm{TeV}$ mass difference.

Results of fits to the $n_{\textrm{b}}$ multiplicity for control regions for the muon channel and with the requirements $3\leq n_{\textrm{jet}}\leq4$, $250<L_T<350~\mathrm{GeV}$, $500<H_T<750~\mathrm{GeV}$, $n_{\textrm{W}}\geq1$, $\Delta \phi<1$. The shaded area shows the fit uncertainty of the total background.

Results of fits to the $n_{\textrm{b}}$ multiplicity for control regions for the muon channel and with the requirements $3\leq n_{\textrm{jet}}\leq4$, $350<L_T<450~\mathrm{GeV}$, $H_T>1000~\mathrm{GeV}$, $n_{\textrm{W}}\geq0$, $\Delta \phi<1$. The shaded area shows the fit uncertainty of the total background.

Jet multiplicity distribution after the single-lepton baseline selection excluding the SRs for the multi-b analysis. The simulation is normalized to data with the SF mentioned in the plot.

Jet multiplicity distribution after the single-lepton baseline selection excluding the SRs for the the zero-b analysis (right). The simulation is normalized to data with the SF mentioned in the plot.

Jet multiplicity distribution in the dilepton CRs for the multi-b analysis. The simulation is normalized to data with the SF mentioned in the plot.

Jet multiplicity distribution in the dilepton CRs for the zero-b analysis. The simulation is normalized to data with the SF mentioned in the plot.

The double ratio of the single-lepton and dilepton ratio between data and simulation together with fit results and their uncertainties is shown for the multi-b analysis. The fits are performed for each data-taking year; 2018 is shown as an example.

The double ratio of the single-lepton and dilepton ratio between data and simulation together with fit results and their uncertainties is shown for the zero-b analysis. The fits are performed for each data-taking year; 2018 is shown as an example.

The prefit $L_{\mathrm{P}}$ distribution for selected electron candidates in the baseline QCD selection, with modified requirements of $n_{\text{jet}}\in[3,4]$ and $n_{\mathrm{b}}=0$.

The prefit $L_{\mathrm{P}}$ distribution for anti-selected electron candidates in the baseline QCD selection, with modified requirements of $n_{\text{jet}}\in[3,4]$ and $n_{\mathrm{b}}=0$.

Observed event yields in the MB SRs of the multi-b analysis compared to signal and background predictions. The relative fraction of the different SM EW background contributions determined in simulation is shown by the stacked, colored histograms, normalized so that their sum is equal to the background estimated using data control regions. The QCD background is predicted using the $L_p$ method. The signal is shown for two representative combinations of (gluino, neutralino) masses with large (2.2, 0.1) $\mathrm{TeV}$ and small (1.8, 1.3) $\mathrm{TeV}$ mass differences.

Observed event yields in the MB SRs of the zero-b analysis compared to signal and background predictions. The $\textrm{W}$+jets, $\textrm{t}\bar{\textrm{t}}$+jets, and QCD predictions are extracted from data control samples, while the other background contributions are estimated from simulation. The signal is shown for two representative combinations of (gluino, neutralino) masses with large (2.2, 0.1) $\mathrm{TeV}$ and small (1.8, 1.3) $\mathrm{TeV}$ mass differences.

Cross section limits at 95% CL for the T1tttt (left) model, as functions of the gluino and LSP masses, assuming a branching fraction of 100%. The mass of the intermediate chargino is taken to be halfway between the gluino and the neutralino masses. The solid black (dashed red) lines correspond to the observed (expected) mass limits, with the thicker lines representing the central values and the thinner lines representing the $\pm1\sigma$ uncertainty bands related to the theoretical (experimental) uncertainties.

Cross section limits at 95% CL for the T1tttt model, as functions of the gluino and LSP masses, assuming a branching fraction of 100%. The mass of the intermediate chargino is taken to be halfway between the gluino and the neutralino masses. The solid black (dashed red) lines correspond to the observed (expected) mass limits, with the thicker lines representing the central values and the thinner lines representing the $\pm1\sigma$ uncertainty bands related to the theoretical (experimental) uncertainties.

Cross section limits at 95% CL for the T1tttt model, as functions of the gluino and LSP masses, assuming a branching fraction of 100%. The mass of the intermediate chargino is taken to be halfway between the gluino and the neutralino masses. The solid black (dashed red) lines correspond to the observed (expected) mass limits, with the thicker lines representing the central values and the thinner lines representing the $\pm1\sigma$ uncertainty bands related to the theoretical (experimental) uncertainties.

Cross section limits at 95% CL for the T1tttt model, as functions of the gluino and LSP masses, assuming a branching fraction of 100%. The mass of the intermediate chargino is taken to be halfway between the gluino and the neutralino masses. The solid black (dashed red) lines correspond to the observed (expected) mass limits, with the thicker lines representing the central values and the thinner lines representing the $\pm1\sigma$ uncertainty bands related to the theoretical (experimental) uncertainties.

Cross section limits at 95% CL for the T1tttt model, as functions of the gluino and LSP masses, assuming a branching fraction of 100%. The mass of the intermediate chargino is taken to be halfway between the gluino and the neutralino masses. The solid black (dashed red) lines correspond to the experved (expected) mass limits, with the thicker lines representing the central values and the thinner lines representing the $\pm1\sigma$ uncertainty bands related to the theoretical (experimental) uncertainties.

Cross section limits at 95% CL for the T1tttt model, as functions of the gluino and LSP masses, assuming a branching fraction of 100%. The mass of the intermediate chargino is taken to be halfway between the gluino and the neutralino masses. The solid black (dashed red) lines correspond to the experved (expected) mass limits, with the thicker lines representing the central values and the thinner lines representing the $\pm1\sigma$ uncertainty bands related to the theoretical (experimental) uncertainties.

Cross section limits at 95% CL for the T1tttt model, as functions of the gluino and LSP masses, assuming a branching fraction of 100%. The mass of the intermediate chargino is taken to be halfway between the gluino and the neutralino masses. The solid black (dashed red) lines correspond to the experved (expected) mass limits, with the thicker lines representing the central values and the thinner lines representing the $\pm1\sigma$ uncertainty bands related to the theoretical (experimental) uncertainties.

Cross section limits at 95% CL for the T5qqqqWW model, as functions of the gluino and LSP masses, assuming a branching fraction of 100%. The mass of the intermediate chargino is taken to be halfway between the gluino and the neutralino masses. The solid black (dashed red) lines correspond to the observed (expected) mass limits, with the thicker lines representing the central values and the thinner lines representing the $\pm1\sigma$ uncertainty bands related to the theoretical (experimental) uncertainties.

Cross section limits at 95% CL for the T5qqqqWW model, as functions of the gluino and LSP masses, assuming a branching fraction of 100%. The mass of the intermediate chargino is taken to be halfway between the gluino and the neutralino masses. The solid black (dashed red) lines correspond to the observed (expected) mass limits, with the thicker lines representing the central values and the thinner lines representing the $\pm1\sigma$ uncertainty bands related to the theoretical (experimental) uncertainties.

Cross section limits at 95% CL for the T5qqqqWW model, as functions of the gluino and LSP masses, assuming a branching fraction of 100%. The mass of the intermediate chargino is taken to be halfway between the gluino and the neutralino masses. The solid black (dashed red) lines correspond to the observed (expected) mass limits, with the thicker lines representing the central values and the thinner lines representing the $\pm1\sigma$ uncertainty bands related to the theoretical (experimental) uncertainties.

Cross section limits at 95% CL for the T5qqqqWW model, as functions of the gluino and LSP masses, assuming a branching fraction of 100%. The mass of the intermediate chargino is taken to be halfway between the gluino and the neutralino masses. The solid black (dashed red) lines correspond to the observed (expected) mass limits, with the thicker lines representing the central values and the thinner lines representing the $\pm1\sigma$ uncertainty bands related to the theoretical (experimental) uncertainties.

Cross section limits at 95% CL for the T5qqqqWW model, as functions of the gluino and LSP masses, assuming a branching fraction of 100%. The mass of the intermediate chargino is taken to be halfway between the gluino and the neutralino masses. The solid black (dashed red) lines correspond to the experved (expected) mass limits, with the thicker lines representing the central values and the thinner lines representing the $\pm1\sigma$ uncertainty bands related to the theoretical (experimental) uncertainties.

Cross section limits at 95% CL for the T5qqqqWW model, as functions of the gluino and LSP masses, assuming a branching fraction of 100%. The mass of the intermediate chargino is taken to be halfway between the gluino and the neutralino masses. The solid black (dashed red) lines correspond to the experved (expected) mass limits, with the thicker lines representing the central values and the thinner lines representing the $\pm1\sigma$ uncertainty bands related to the theoretical (experimental) uncertainties.

Cross section limits at 95% CL for the T5qqqqWW model, as functions of the gluino and LSP masses, assuming a branching fraction of 100%. The mass of the intermediate chargino is taken to be halfway between the gluino and the neutralino masses. The solid black (dashed red) lines correspond to the experved (expected) mass limits, with the thicker lines representing the central values and the thinner lines representing the $\pm1\sigma$ uncertainty bands related to the theoretical (experimental) uncertainties.

Observed number of events in the MB SR bins of the multi-b analysis. All bins are defined with $\Delta\phi > 0.75$.

Observed number of events in the MB SR bins of the zero-b analysis.

The simplified likelihood can be constructed using this covariance matrix of nuisance parameters in the signal region (MB SR). The bin contents have been aggregated accross the three years to simplify the likelihood.

Selection efficiency for the multi-b signal for the SRs.

The simplified likelihood can be constructed using this covariance matrix of nuisance parameters in the signal region (MB SR). The bins were aggregated across HT to stabilize the simplified likelihood.

Selection efficiency for the zero-b signal for the SRs. The bins correspond to the aggregated bins that were used for the covariance matrix.