Observed (black markers) and expected distributions of number of jets after event selection. The hatched (grey) areas denote the systematic (total) uncertainties in the expected yields. Events from all data-taking periods and all channels are combined. The lower panel of each plot shows the ratio between observed and expected distributions. The last bin includes all events above the plotted range. The entry Background corresponds to the sum of all the SM predictions.

Observed (black markers) and expected distributions of number of b tagged jets after event selection. The hatched (grey) areas denote the systematic (total) uncertainties in the expected yields. Events from all data-taking periods and all channels are combined. The lower panel of each plot shows the ratio between observed and expected distributions. The last bin includes all events above the plotted range. The entry Background corresponds to the sum of all the SM predictions.

Difference between $p_{\mathrm{T,gen.}}^\text{miss}$ and $p_{\mathrm{T,rec.}}^\text{miss}$ as a function of the $p_{\mathrm{T,gen.}}^\text{miss}$ for signal events. The mean difference between the generated and the $p_{\mathrm{T,rec.}}^\text{miss}$ per bin is shown as solid line. The results for $p_{\mathrm{T}}^\text{miss}$ corrected by the DNN regression (light blue), derived with the PUPPI algorithm (red), and the PF algorithm (orange) are shown. A simulated sample for the 2018 data-taking period is used.

Difference between $p_{\mathrm{T,gen.}}^\text{miss}$ and $p_{\mathrm{T,rec.}}^\text{miss}$ as a function of the $p_{\mathrm{T,gen.}}^\text{miss}$ for signal events. The dashed line shows the standard deviation $\sigma$, which corresponds to the resolution of the $p_{\mathrm{T,gen.}}^\text{miss}$ and $p_{\mathrm{T,rec.}}^\text{miss}$ difference. The results for $p_{\mathrm{T}}^\text{miss}$ corrected by the DNN regression (light blue), derived with the PUPPI algorithm (red), and the PF algorithm (orange) are shown. A simulated sample for the 2018 data-taking period is used.

Difference between $p_{\mathrm{T,gen.}}^\text{miss}$ and $p_{\mathrm{T,rec.}}^\text{miss}$ as a function of the number of primary vertices for signal events. The mean difference between the generated and the $p_{\mathrm{T,rec.}}^\text{miss}$ per bin is shown as solid line. The results for $p_{\mathrm{T}}^\text{miss}$ corrected by the DNN regression (light blue), derived with the PUPPI algorithm (red), and the PF algorithm (orange) are shown. A simulated sample for the 2018 data-taking period is used.

Difference between $p_{\mathrm{T,gen.}}^\text{miss}$ and $p_{\mathrm{T,rec.}}^\text{miss}$ as a function of the $p_{\mathrm{T,gen.}}^\text{miss}$ for signal events. The dashed line shows the standard deviation $\sigma$, which corresponds to the resolution of the $p_{\mathrm{T,gen.}}^\text{miss}$ and $p_{\mathrm{T,rec.}}^\text{miss}$ difference. The results for $p_{\mathrm{T}}^\text{miss}$ corrected by the DNN regression (light blue), derived with the PUPPI algorithm (red), and the PF algorithm (orange) are shown. A simulated sample for the 2018 data-taking period is used.

Results of the $\chi^{2}$ tests for the absolute and normalized differential cross section measurements for each of the predictions. The $\chi^{2}$ values including uncertainties on the predictions are given in parentheses in the table in the paper and in a separate column here.

The p-value of the $\chi^{2}$ tests for the absolute and normalized cross section measurements for each of the predictions. The resulting p-values including uncertainties on the predictions are given in parentheses in the table in the paper and in a separate column here.

Breakdown of the relative contribution from experimental uncertainties in the differential cross section measurement as a function of $p_{\text{T}}^{\nu\nu}$. The statistical uncertainty (dark grey) takes the size of the available simulated samples and the recorded data into account. The last bin includes all events above the plotted range.

Breakdown of the relative contribution from theory uncertainties in the differential cross section measurement as a function of $p_{\text{T}}^{\nu\nu}$. The statistical uncertainty (dark grey) takes the size of the available simulated samples and the recorded data into account. The last bin includes all events above the plotted range.

Breakdown of the relative contribution from experimental uncertainties in the differential cross section measurement as a function of $\text{min}[\Delta\phi(\vec{p}_{\text{T}}^{\nu\nu},\vec{p}_{\text{T}}^{\ell})]$. The statistical uncertainty (dark grey) takes the size of the available simulated samples and the recorded data into account. The last bin includes all events above the plotted range.

Breakdown of the relative contribution from theory uncertainties in the differential cross section measurement as a function of $\text{min}[\Delta\phi(\vec{p}_{\text{T}}^{\nu\nu},\vec{p}_{\text{T}}^{\ell})]$. The statistical uncertainty (dark grey) takes the size of the available simulated samples and the recorded data into account. The last bin includes all events above the plotted range.

Breakdown of the relative contribution from experimental uncertainties in the differential cross section measurement as a function of $p_{\text{T}}^{\nu\nu}$ and $\text{min}[\Delta\phi(\vec{p}_{\text{T}}^{\nu\nu},\vec{p}_{\text{T}}^{\ell})]$ for the azimuthal angle range 0<$\phi$<0.56. Each group of four bins corresponds to $p_{\text{T}}^{\nu\nu}$ bins, and $\text{min}[\Delta\phi(\vec{p}_{\text{T}}^{\nu\nu},\vec{p}_{\text{T}}^{\ell})]$ bin edges are indicated by vertical solid lines. The statistical uncertainty (dark grey) takes the size of the available simulated samples and the recorded data into account. The last bin includes all events above the plotted range.

Breakdown of the relative contribution from experimental uncertainties in the differential cross section measurement as a function of $p_{\text{T}}^{\nu\nu}$ and $\text{min}[\Delta\phi(\vec{p}_{\text{T}}^{\nu\nu},\vec{p}_{\text{T}}^{\ell})]$ for the azimuthal angle range 0.56<$\phi$<1.08. Each group of four bins corresponds to $p_{\text{T}}^{\nu\nu}$ bins, and $\text{min}[\Delta\phi(\vec{p}_{\text{T}}^{\nu\nu},\vec{p}_{\text{T}}^{\ell})]$ bin edges are indicated by vertical solid lines. The statistical uncertainty (dark grey) takes the size of the available simulated samples and the recorded data into account. The last bin includes all events above the plotted range.

Breakdown of the relative contribution from experimental uncertainties in the differential cross section measurement as a function of $p_{\text{T}}^{\nu\nu}$ and $\text{min}[\Delta\phi(\vec{p}_{\text{T}}^{\nu\nu},\vec{p}_{\text{T}}^{\ell})]$ for the azimuthal angle range 1.08<$\phi$<3.14. Each group of four bins corresponds to $p_{\text{T}}^{\nu\nu}$ bins, and $\text{min}[\Delta\phi(\vec{p}_{\text{T}}^{\nu\nu},\vec{p}_{\text{T}}^{\ell})]$ bin edges are indicated by vertical solid lines. The statistical uncertainty (dark grey) takes the size of the available simulated samples and the recorded data into account. The last bin includes all events above the plotted range.

Breakdown of the relative contribution from theory uncertainties in the differential cross section measurement as a function of $p_{\text{T}}^{\nu\nu}$ and $\text{min}[\Delta\phi(\vec{p}_{\text{T}}^{\nu\nu},\vec{p}_{\text{T}}^{\ell})]$ for the azimuthal angle range 0<$\phi$<0.56. Each group of four bins corresponds to $p_{\text{T}}^{\nu\nu}$ bins, and $\text{min}[\Delta\phi(\vec{p}_{\text{T}}^{\nu\nu},\vec{p}_{\text{T}}^{\ell})]$ bin edges are indicated by vertical solid lines. The statistical uncertainty (dark grey) takes the size of the available simulated samples and the recorded data into account. The last bin includes all events above the plotted range.

Breakdown of the relative contribution from theory uncertainties in the differential cross section measurement as a function of $p_{\text{T}}^{\nu\nu}$ and $\text{min}[\Delta\phi(\vec{p}_{\text{T}}^{\nu\nu},\vec{p}_{\text{T}}^{\ell})]$ for the azimuthal angle range 0.56<$\phi$<1.08. Each group of four bins corresponds to $p_{\text{T}}^{\nu\nu}$ bins, and $\text{min}[\Delta\phi(\vec{p}_{\text{T}}^{\nu\nu},\vec{p}_{\text{T}}^{\ell})]$ bin edges are indicated by vertical solid lines. The statistical uncertainty (dark grey) takes the size of the available simulated samples and the recorded data into account. The last bin includes all events above the plotted range.

Breakdown of the relative contribution from theory uncertainties in the differential cross section measurement as a function of $p_{\text{T}}^{\nu\nu}$ and $\text{min}[\Delta\phi(\vec{p}_{\text{T}}^{\nu\nu},\vec{p}_{\text{T}}^{\ell})]$ for the azimuthal angle range 1.08<$\phi$<3.14. Each group of four bins corresponds to $p_{\text{T}}^{\nu\nu}$ bins, and $\text{min}[\Delta\phi(\vec{p}_{\text{T}}^{\nu\nu},\vec{p}_{\text{T}}^{\ell})]$ bin edges are indicated by vertical solid lines. The statistical uncertainty (dark grey) takes the size of the available simulated samples and the recorded data into account. The last bin includes all events above the plotted range.

The observed (black markers) and simulated distributions of $p_{\mathrm{T,DNN}}^\text{miss}$ is shown. Events from all data-taking periods and all channels are combined. The hatched (grey) areas indicate the systematic (total) uncertainty in the simulation. The lower panel of each plot shows the ratio of observed data to the expectation from MC simulation in each bin. The last bin includes all events above the plotted range.

The observed (black markers) and simulated distributions of $\text{min}[\Delta\phi(\vec{p}_{\text{T, DNN}}^{\text{miss}},\vec{p}_{\text{T}}^{\ell})]$ is shown. Events from all data-taking periods and all channels are combined. The hatched (grey) areas indicate the systematic (total) uncertainty in the simulation. The lower panel of each plot shows the ratio of observed data to the expectation from MC simulation in each bin. The last bin includes all events above the plotted range.

The observed (black markers) and simulated two-dimensional distribution of $p_{\mathrm{T,DNN}}^\text{miss}$ and $\text{min}[\Delta\phi(\vec{p}_{\text{T, DNN}}^{\text{miss}},\vec{p}_{\text{T}}^{\ell})]$ for the azimuthal angle range 0<$\phi$<0.28 is shown. Events from all data-taking periods and all channels are combined. The hatched (grey) areas indicate the systematic (total) uncertainty in the simulation. The lower panel of each plot shows the ratio of observed data to the expectation from MC simulation in each bin. The last bin includes all events above the plotted range.

The observed (black markers) and simulated two-dimensional distribution of $p_{\mathrm{T,DNN}}^\text{miss}$ and $\text{min}[\Delta\phi(\vec{p}_{\text{T, DNN}}^{\text{miss}},\vec{p}_{\text{T}}^{\ell})]$ for the azimuthal angle range 0.28<$\phi$<0.56 is shown. Events from all data-taking periods and all channels are combined. The hatched (grey) areas indicate the systematic (total) uncertainty in the simulation. The lower panel of each plot shows the ratio of observed data to the expectation from MC simulation in each bin. The last bin includes all events above the plotted range.

The observed (black markers) and simulated two-dimensional distribution of $p_{\mathrm{T,DNN}}^\text{miss}$ and $\text{min}[\Delta\phi(\vec{p}_{\text{T, DNN}}^{\text{miss}},\vec{p}_{\text{T}}^{\ell})]$ for the azimuthal angle range 0.56<$\phi$<0.82 is shown. Events from all data-taking periods and all channels are combined. The hatched (grey) areas indicate the systematic (total) uncertainty in the simulation. The lower panel of each plot shows the ratio of observed data to the expectation from MC simulation in each bin. The last bin includes all events above the plotted range.

The observed (black markers) and simulated two-dimensional distribution of $p_{\mathrm{T,DNN}}^\text{miss}$ and $\text{min}[\Delta\phi(\vec{p}_{\text{T, DNN}}^{\text{miss}},\vec{p}_{\text{T}}^{\ell})]$ for the azimuthal angle range 0.82<$\phi$<1.08 is shown. Events from all data-taking periods and all channels are combined. The hatched (grey) areas indicate the systematic (total) uncertainty in the simulation. The lower panel of each plot shows the ratio of observed data to the expectation from MC simulation in each bin. The last bin includes all events above the plotted range.

The observed (black markers) and simulated two-dimensional distribution of $p_{\mathrm{T,DNN}}^\text{miss}$ and $\text{min}[\Delta\phi(\vec{p}_{\text{T, DNN}}^{\text{miss}},\vec{p}_{\text{T}}^{\ell})]$ for the azimuthal angle range 1.08<$\phi$<2.14 is shown. Events from all data-taking periods and all channels are combined. The hatched (grey) areas indicate the systematic (total) uncertainty in the simulation. The lower panel of each plot shows the ratio of observed data to the expectation from MC simulation in each bin. The last bin includes all events above the plotted range.

The observed (black markers) and simulated two-dimensional distribution of $p_{\mathrm{T,DNN}}^\text{miss}$ and $\text{min}[\Delta\phi(\vec{p}_{\text{T, DNN}}^{\text{miss}},\vec{p}_{\text{T}}^{\ell})]$ for the azimuthal angle range 2.14<$\phi$<3.2 is shown. Events from all data-taking periods and all channels are combined. The hatched (grey) areas indicate the systematic (total) uncertainty in the simulation. The lower panel of each plot shows the ratio of observed data to the expectation from MC simulation in each bin. The last bin includes all events above the plotted range.

Result of the closure test based on simulation accounting for potential BSM contributions based on a top squark pair production scenario with a stop mass of 525 GeV and a neutralino mass of 350 GeV. The potential BSM contribution is scaled by a factor of ten. The test is performed for the $p_{\text{T}}^{\nu\nu}$ using the nominal (black), the regularized (orange), and the bin-by-bin unfolding (purple), based on all data-taking periods combined. The unfolded distributions are compared to the expected distribution (red) based on the sum of the nominal dileptonic $t\bar{t}$ signal sample and BSM signal with the corresponding $\chi^2/\text{ndf}$ values given in the legend in square brackets. The distribution used for the response matrix, is shown in blue. The error bars correspond to the statistical uncertainty. The lower part shows the ratios between the unfolded and the expected distributions.

Result of the closure test based on simulation. The potential BSM contribution is scaled by a factor of ten. The test is performed for the 2D measurement of $p_{\text{T}}^{\nu\nu}$ and $\text{min}[\Delta\phi(\vec{p}_{\text{T}}^{\nu\nu},\vec{p}_{\text{T}}^{\ell})]$ in the azimuthal angle range 0<$\phi$<0.56 using the nominal (black), the regularized (orange), and the bin-by-bin unfolding (purple), based on all data-taking periods combined. The unfolded distributions are compared to the expected distribution (red) based on the sum of the nominal dileptonic $t\bar{t}$ signal sample and BSM signal with the corresponding $\chi^2/\text{ndf}$ values given in the legend. The nominal distribution, used for the response matrix, is shown in blue. The error bars correspond to the statistical uncertainty. The lower part shows the ratios between the unfolded and the expected distributions.

Result of the closure test based on simulation. The potential BSM contribution is scaled by a factor of ten. The test is performed for the 2D measurement of $p_{\text{T}}^{\nu\nu}$ and $\text{min}[\Delta\phi(\vec{p}_{\text{T}}^{\nu\nu},\vec{p}_{\text{T}}^{\ell})]$ in the azimuthal angle range 0.56<$\phi$<1.08 using the nominal (black), the regularized (orange), and the bin-by-bin unfolding (purple), based on all data-taking periods combined. The unfolded distributions are compared to the expected distribution (red) based on the sum of the nominal dileptonic $t\bar{t}$ signal sample and BSM signal with the corresponding $\chi^2/\text{ndf}$ values given in the legend. The nominal distribution, used for the response matrix, is shown in blue. The error bars correspond to the statistical uncertainty. The lower part shows the ratios between the unfolded and the expected distributions.

Result of the closure test based on simulation. The potential BSM contribution is scaled by a factor of ten. The test is performed for the 2D measurement of $p_{\text{T}}^{\nu\nu}$ and $\text{min}[\Delta\phi(\vec{p}_{\text{T}}^{\nu\nu},\vec{p}_{\text{T}}^{\ell})]$ in the azimuthal angle range 1.08<$\phi$<3.14 using the nominal (black), the regularized (orange), and the bin-by-bin unfolding (purple), based on all data-taking periods combined. The unfolded distributions are compared to the expected distribution (red) based on the sum of the nominal dileptonic $t\bar{t}$ signal sample and BSM signal with the corresponding $\chi^2/\text{ndf}$ values given in the legend. The nominal distribution, used for the response matrix, is shown in blue. The error bars correspond to the statistical uncertainty. The lower part shows the ratios between the unfolded and the expected distributions.

The measured differential signal cross section (black markers) as a function of $p_{\text{T}}^{\nu\nu}$ is shown. The theoretical predictions from POWHEG+PYTHIA (dark red), POWHEG+HERWIG (orange), MC@NLO+PYTHIA (purple), and the fixed-order NLO (light blue) and NNLO (brown) calculations are compared to the measurement. The total (statistical) uncertainty in the measurement is shown as an orange (dark grey) band. The lower panel of each plot shows the ratio between theoretical predictions and the measurement.

The measured differential signal cross section (black markers) as a function of $\text{min}[\Delta\phi(\vec{p}_{\text{T}}^{\nu\nu},\vec{p}_{\text{T}}^{\ell})]$ is shown. The theoretical predictions from POWHEG+PYTHIA (dark red), POWHEG+HERWIG (orange), MC@NLO+PYTHIA (purple), and the fixed-order NLO (light blue) and NNLO (brown) calculations are compared to the measurement. The total (statistical) uncertainty in the measurement is shown as an orange (dark grey) band. The lower panel of each plot shows the ratio between theoretical predictions and the measurement.

The measured two-dimensional differential signal cross section (black markers) as a function of $p_{\text{T}}^{\nu\nu}$ and $\text{min}[\Delta\phi(\vec{p}_{\text{T}}^{\nu\nu},\vec{p}_{\text{T}}^{\ell})]$ for the azimuthal angle range 0<$\phi$<0.56 is shown. The theoretical predictions from POWHEG+PYTHIA (dark red), POWHEG+HERWIG (orange), MC@NLO+PYTHIA (purple), and the fixed-order NLO (light blue) and NNLO (brown) calculations are compared to the measurement. The total (statistical) uncertainty in the measurement is shown as an orange (dark grey) band. The lower panel of each plot shows the ratio between theoretical predictions and the measurement.

The measured two-dimensional differential signal cross section (black markers) as a function of $p_{\text{T}}^{\nu\nu}$ and $\text{min}[\Delta\phi(\vec{p}_{\text{T}}^{\nu\nu},\vec{p}_{\text{T}}^{\ell})]$ for the azimuthal angle range 0.56<$\phi$<1.08 is shown. The theoretical predictions from POWHEG+PYTHIA (dark red), POWHEG+HERWIG (orange), MC@NLO+PYTHIA (purple), and the fixed-order NLO (light blue) and NNLO (brown) calculations are compared to the measurement. The total (statistical) uncertainty in the measurement is shown as an orange (dark grey) band. The lower panel of each plot shows the ratio between theoretical predictions and the measurement.

The measured two-dimensional differential signal cross section (black markers) as a function of $p_{\text{T}}^{\nu\nu}$ and $\text{min}[\Delta\phi(\vec{p}_{\text{T}}^{\nu\nu},\vec{p}_{\text{T}}^{\ell})]$ for the azimuthal angle range 1.08<$\phi$<3.14 is shown. The theoretical predictions from POWHEG+PYTHIA (dark red), POWHEG+HERWIG (orange), MC@NLO+PYTHIA (purple), and the fixed-order NLO (light blue) and NNLO (brown) calculations are compared to the measurement. The total (statistical) uncertainty in the measurement is shown as an orange (dark grey) band. The lower panel of each plot shows the ratio between theoretical predictions and the measurement.

The normalized measured differential signal cross section (black markers) as a function of $p_{\text{T}}^{\nu\nu}$ is shown. The theoretical predictions from POWHEG+PYTHIA (dark red), POWHEG+HERWIG (orange), MC@NLO+PYTHIA (purple), and the fixed-order NLO (light blue) and NNLO (brown) calculations are compared to the measurement. The total (statistical) uncertainty in the measurement is shown as an orange (dark grey) band. The lower panel of each plot shows the ratio between theoretical predictions and the measurement.

The normalized measured differential signal cross section (black markers) as a function of $\text{min}[\Delta\phi(\vec{p}_{\text{T}}^{\nu\nu},\vec{p}_{\text{T}}^{\ell})]$ is shown. The theoretical predictions from POWHEG+PYTHIA (dark red), POWHEG+HERWIG (orange), MC@NLO+PYTHIA (purple), and the fixed-order NLO (light blue) and NNLO (brown) calculations are compared to the measurement. The total (statistical) uncertainty in the measurement is shown as an orange (dark grey) band. The lower panel of each plot shows the ratio between theoretical predictions and the measurement.

The normalized measured two-dimensional differential signal cross section (black markers) as a function of $p_{\text{T}}^{\nu\nu}$ and $\text{min}[\Delta\phi(\vec{p}_{\text{T}}^{\nu\nu},\vec{p}_{\text{T}}^{\ell})]$ for the azimuthal angle range 0<$\phi$<0.56 is shown. The theoretical predictions from POWHEG+PYTHIA (dark red), POWHEG+HERWIG (orange), MC@NLO+PYTHIA (purple), and the fixed-order NLO (light blue) and NNLO (brown) calculations are compared to the measurement. The total (statistical) uncertainty in the measurement is shown as an orange (dark grey) band. The lower panel of each plot shows the ratio between theoretical predictions and the measurement.

The normalized measured two-dimensional differential signal cross section (black markers) as a function of $p_{\text{T}}^{\nu\nu}$ and $\text{min}[\Delta\phi(\vec{p}_{\text{T}}^{\nu\nu},\vec{p}_{\text{T}}^{\ell})]$ for the azimuthal angle range 0.56<$\phi$<1.08 is shown. The theoretical predictions from POWHEG+PYTHIA (dark red), POWHEG+HERWIG (orange), MC@NLO+PYTHIA (purple), and the fixed-order NLO (light blue) and NNLO (brown) calculations are compared to the measurement. The total (statistical) uncertainty in the measurement is shown as an orange (dark grey) band. The lower panel of each plot shows the ratio between theoretical predictions and the measurement.

The normalized measured two-dimensional differential signal cross section (black markers) as a function of $p_{\text{T}}^{\nu\nu}$ and $\text{min}[\Delta\phi(\vec{p}_{\text{T}}^{\nu\nu},\vec{p}_{\text{T}}^{\ell})]$ for the azimuthal angle range 1.08<$\phi$<3.14 is shown. The theoretical predictions from POWHEG+PYTHIA (dark red), POWHEG+HERWIG (orange), MC@NLO+PYTHIA (purple), and the fixed-order NLO (light blue) and NNLO (brown) calculations are compared to the measurement. The total (statistical) uncertainty in the measurement is shown as an orange (dark grey) band. The lower panel of each plot shows the ratio between theoretical predictions and the measurement.

Distribution of $m_{\mathrm{T},3l}$ in the JNLow SR after the background-only fit. The uncertainty on the expected number of background events includes all statistical and systematic post-fit uncertainties with the correlations between various background sources taken into account.

Distribution of $H_\text{T} + E_\text{T}^\text{miss}$ in the Q0 SR after the background-only fit. The uncertainty on the expected number of background events includes all statistical and systematic post-fit uncertainties with the correlations between various background sources taken into account.

Distribution of $H_\text{T} + E_\text{T}^\text{miss}$ in the Q2 SR after the background-only fit. The uncertainty on the expected number of background events includes all statistical and systematic post-fit uncertainties with the correlations between various background sources taken into account.

Distribution of $m_{\mathrm{T},3l}$ in the ZL-CR after the background-only fit.

Distribution of $m_{\mathrm{T},3l}$ in the Fake-CR after the background-only fit.

Distribution of $H_\text{T} + E_\text{T}^\text{miss}$ in the Q0 DB-CR after the background-only fit.

Distribution of $H_\text{T} + E_\text{T}^\text{miss}$ in the Q0 RT-CR after the background-only fit.

Expected and observed exclusion limit for the combination of the two- (from Ref. EXOT-2018-33), three- and four-lepton channels, for the type-III seesaw process with the corresponding one- and two-standard-deviation uncertainty bands, showing the 95% CL upper limit on the cross-section.

Expected and observed 95% ( $CL_s$ ) exclusion limits in the three lepton channel for the type-III seesaw process with the corresponding one- and two-standard-deviation bands, showing the 95% CL upper limit on the cross-section.

Expected and observed 95% ( $CL_s$ ) exclusion limits in the four lepton channel for the type-III seesaw process with the corresponding one- and two-standard-deviation bands, showing the 95% CL upper limit on the cross-section.

Cross-sections of signal Monte Carlo samples for each mass point considered in this analysis. Leading order cross-sections ( $\sigma_{LO}$ ) are computed by the generator and then rescaled to next-to-leading cross-sections ( $\sigma_{NLO+NLL}$ ), with their corresponding uncertainties, using information taken from Refs. C1C1 and N2C1.

Expected signal and background yields after each of the analysis selection cuts for the 800 GeV mass hypothesis in the ZL SR. Preselection represents events with at least three leptons.

Expected signal and background yields after each of the analysis selection cuts for the 800 GeV mass hypothesis in the ZLVeto SR. Preselection represents events with at least three leptons.

Expected signal and background yields after each of the analysis selection cuts for the 800 GeV mass hypothesis in the JNLow SR. Preselection represents events with at least three leptons.

Expected signal and background yields after each of the analysis selection cuts for the 800 GeV mass hypothesis in the Q0 SR. Preselection represents events with at least three leptons.

Expected signal and background yields after each of the analysis selection cuts for the 800 GeV mass hypothesis in the Q2 SR. Preselection represents events with at least three leptons.

Expected signal and background yields after each of the analysis selection cuts for the 800 GeV mass hypothesis in the ZL CR. Preselection represents events with at least three leptons.

Expected signal and background yields after each of the analysis selection cuts for the 800 GeV mass hypothesis in the Q0-DB CR. Preselection represents events with at least three leptons.

Expected signal and background yields after each of the analysis selection cuts for the 800 GeV mass hypothesis in the Q0-RT CR. Preselection represents events with at least three leptons.

Expected background yields and observed data after the background-only fit, in the three-lepton CRs and VRs.

Expected background yields and observed data after the background-only fit, in the four-lepton CRs and VRs.

Expected and observed 95% ( $CL_s$ ) exclusion limits in the three and four lepton channels for the type-III seesaw process with the corresponding one- and two-standard-deviation bands, showing the 95% CL upper limit on the cross-section.

Expected signal yields after each of the analysis selection cuts for the 800 GeV mass point. Total expected events represents all type-III seesaw events expected for integrated luminosity 139 fb$^{-1}$. Only events with at least two leptons were generated for this analysis.

Distribution of $H_\text{T} + E_\text{T}^\text{miss}$ in the opposite-sign electron-electron signal region after the background-only fit.

Distribution of $H_\text{T} + E_\text{T}^\text{miss}$ in the opposite-sign electron-muon signal region after the background-only fit.

Distribution of $H_\text{T} + E_\text{T}^\text{miss}$ in the opposite-sign muon-muon signal region after the background-only fit.

Distribution of $H_\text{T} + E_\text{T}^\text{miss}$ in the same-sign electron-electron signal region after the background-only fit.

Distribution of $H_\text{T} + E_\text{T}^\text{miss}$ in the same-sign electron-muon signal region after the background-only fit.

Distribution of $H_\text{T} + E_\text{T}^\text{miss}$ in the same-sign muon-muon signal region after the background-only fit.