Predictions of a leading order (LO) QCD simulation, normalized to an integrated luminosity of 138 fb$^{-1}$. The number of events are examined within bins of the four-jet mass and the ratio $\alpha$, which is the average dijet mass divided by the four-jet mass.

The 68% probability contour in the $m_{\mathrm{4j}}$ vs. $\overline{m}_{\mathrm{2j}}$ plane from a signal simulation of a diquark with a width of 1.5% and a mass of 8.4 TeV, decaying to a pair of vector-like quarks, each with a mass of 2.1 TeV.

The 68% probability contour in the $m_{\mathrm{4j}}$ vs. $\overline{m}_{\mathrm{2j}}$ plane from a signal simulation of a diquark with a width of 5% and a mass of 8.4 TeV, decaying to a pair of vector-like quarks, each with a mass of 2.1 TeV.

The 68% probability contour in the $m_{\mathrm{4j}}$ vs. $\overline{m}_{\mathrm{2j}}$ plane from a signal simulation of a diquark with a width of 10% and a mass of 8.4 TeV, decaying to a pair of vector-like quarks, each with a mass of 2.1 TeV.

The 68% probability contour in the $m_{\mathrm{4j}}$ vs. $\alpha$ plane from a signal simulation of a diquark with a width of 1.5% and a mass of 8.4 TeV, decaying to a pair of vector-like quarks, each with a mass of 2.1 TeV.

The 68% probability contour in the $m_{\mathrm{4j}}$ vs. $\alpha$ plane from a signal simulation of a diquark with a width of 5% and a mass of 8.4 TeV, decaying to a pair of vector-like quarks, each with a mass of 2.1 TeV.

The 68% probability contour in the $m_{\mathrm{4j}}$ vs. $\alpha$ plane from a signal simulation of a diquark with a width of 10% and a mass of 8.4 TeV, decaying to a pair of vector-like quarks, each with a mass of 2.1 TeV.

Signal differential distributions as a function of four-jet mass for $\alpha_{\mathrm{true}}$ = 0.25, diquark masses of 2, 5, 8.6 TeV and various widths, for all $\alpha$ bins inclusively. The integral of each distribution has been normalized to unity.

The product of acceptance, $A$, and efficiency, $\varepsilon$, of a resonant signal with $\alpha_{\mathrm{true}}$ = 0.25 vs. the diquark mass for various diquark widths, and for all $\alpha$ bins inclusively. The acceptance is defined as the fraction of generated events passing the kinematic selection criteria, while the efficiency is the fraction of signal events satisfying $m_{\mathrm{4j}} > 1.6$ TeV. We also show the signal acceptance alone in the curves where $\varepsilon = 1$.

The four-jet mass distribution in data for 0.22 < $\alpha$ < 0.24, fitted with three background-only functions (Dijet-3p, PowExp-3p and ModDijet-3p), each with three free parameters. Examples of predicted diquark resonances with $\alpha_{\mathrm{true}}$ = 0.25, $M_{\mathrm{S}}$ = 8.6 TeV, and $\Gamma/M_{\mathrm{S}}$ = 1.5%, 10% are also shown, with cross sections equal to the observed upper limits at 95% confidence level.

The four-jet mass distribution in data for 0.24 < $\alpha$ < 0.26, fitted with three background-only functions (Dijet-3p, PowExp-3p and ModDijet-3p), each with three free parameters. Examples of predicted diquark resonances with $\alpha_{\mathrm{true}}$ = 0.25, $M_{\mathrm{S}}$ = 8.6 TeV, and $\Gamma/M_{\mathrm{S}}$ = 1.5%, 10% are also shown, with cross sections equal to the observed upper limits at 95% confidence level.

The four-jet mass distribution in data for 0.26 < $\alpha$ < 0.28, fitted with three background-only functions (Dijet-3p, PowExp-3p and ModDijet-3p), each with three free parameters. Examples of predicted diquark resonances with $\alpha_{\mathrm{true}}$ = 0.25, $M_{\mathrm{S}}$ = 8.6 TeV and $\alpha_{\mathrm{true}}$ = 0.29, $M_{\mathrm{S}}$ = 3.6 TeV, each shown for widths of $\Gamma/M_{\mathrm{S}}$ = 1.5% and 10% are also included, with cross sections equal to the observed upper limits at 95% confidence level.

The four-jet mass distribution in data for 0.28 < $\alpha$ < 0.30, fitted with three background-only functions (Dijet-3p, PowExp-3p and ModDijet-3p), each with three free parameters. Examples of predicted diquark resonances with $\alpha_{\mathrm{true}}$ = 0.25, $M_{\mathrm{S}}$ = 8.6 TeV and $\alpha_{\mathrm{true}}$ = 0.29, $M_{\mathrm{S}}$ = 3.6 TeV, each shown for widths of $\Gamma/M_{\mathrm{S}}$ = 1.5% and 10% are also included, with cross sections equal to the observed upper limits at 95% confidence level.

The four-jet mass distribution in data for 0.30 < $\alpha$ < 0.32, fitted with three background-only functions (Dijet-3p, PowExp-3p and ModDijet-3p), each with three free parameters. Examples of predicted diquark resonances with $\alpha_{\mathrm{true}}$ = 0.25, $M_{\mathrm{S}}$ = 8.6 TeV and $\alpha_{\mathrm{true}}$ = 0.29, $M_{\mathrm{S}}$ = 3.6 TeV, each shown for widths of $\Gamma/M_{\mathrm{S}}$ = 1.5% and 10% are also included, with cross sections equal to the observed upper limits at 95% confidence level.

The four-jet mass distribution in data for 0.32 < $\alpha$ < 0.34, fitted with three background-only functions (Dijet-3p, PowExp-3p and ModDijet-3p), each with three free parameters. Examples of predicted diquark resonances with $\alpha_{\mathrm{true}}$ = 0.25, $M_{\mathrm{S}}$ = 8.6 TeV, and $\Gamma/M_{\mathrm{S}}$ = 1.5%, 10% are also shown, with cross sections equal to the observed upper limits at 95% confidence level.

The inclusive four-jet mass distribution in data for $\alpha$ > 0.10, fitted with three background-only functions (Dijet-5p, PowExp-5p and ModDijet-5p), each with five free parameters. Examples of predicted diquark resonances with $\alpha_{\mathrm{true}}$ = 0.25, $M_{\mathrm{S}}$ = 8.6 TeV and $\alpha_{\mathrm{true}}$ = 0.29, $M_{\mathrm{S}}$ = 3.6 TeV, each shown for widths of $\Gamma/M_{\mathrm{S}}$ = 1.5% and 10% are also included, with cross sections equal to the observed upper limits at 95% confidence level.

The observed 95% CL upper limits on the product of the cross section, branching fraction, and acceptance for resonant production of paired dijet resonances, X, with $\alpha_{\mathrm{true}} = M_{\mathrm{X}} / M_{\mathrm{Y}} = 0.25$ and width of the initial resonance Y equal to 1.5%. The corresponding expected limits and their variations at the 1 and 2 standard deviation (s.d.) levels are also included. Limits are compared to predictions for scalar $\mathrm{S}_{\mathrm{uu}}$ and $\mathrm{S}_{\mathrm{dd}}$ diquarks with couplings to pairs of up and down quarks, $y_{\mathrm{uu}}$ and $y_{\mathrm{dd}}$, and to pairs of vector-like quarks, $y_{\chi}$ and $y_{\omega}$, set appropriately in order to generate a mediator width equal to 1.5%.

The observed 95% CL upper limits on the product of the cross section, branching fraction, and acceptance for resonant production of paired dijet resonances, X, with $\alpha_{\mathrm{true}} = M_{\mathrm{X}} / M_{\mathrm{Y}} = 0.25$ and width of the initial resonance Y equal to 5%. The corresponding expected limits and their variations at the 1 and 2 standard deviation (s.d.) levels are also included. Limits are compared to predictions for scalar $\mathrm{S}_{\mathrm{uu}}$ and $\mathrm{S}_{\mathrm{dd}}$ diquarks with couplings to pairs of up and down quarks, $y_{\mathrm{uu}}$ and $y_{\mathrm{dd}}$, and to pairs of vector-like quarks, $y_{\chi}$ and $y_{\omega}$, set appropriately in order to generate a mediator width equal to 5%.

The observed 95% CL upper limits on the product of the cross section, branching fraction, and acceptance for resonant production of paired dijet resonances, X, with $\alpha_{\mathrm{true}} = M_{\mathrm{X}} / M_{\mathrm{Y}} = 0.25$ and width of the initial resonance Y equal to 10%. The corresponding expected limits and their variations at the 1 and 2 standard deviation (s.d.) levels are also included. Limits are compared to predictions for scalar $\mathrm{S}_{\mathrm{uu}}$ and $\mathrm{S}_{\mathrm{dd}}$ diquarks with couplings to pairs of up and down quarks, $y_{\mathrm{uu}}$ and $y_{\mathrm{dd}}$, and to pairs of vector-like quarks, $y_{\chi}$ and $y_{\omega}$, set appropriately in order to generate a mediator width equal to 10%.

The observed 95% CL upper limits on the product of the cross section, branching fraction, and acceptance for resonant production of paired dijet resonances, X, with $\alpha_{\mathrm{true}} = M_{\mathrm{X}} / M_{\mathrm{Y}} = 0.11$ and width of the initial resonance Y equal to 10%. The corresponding expected limits and their variations at the 1 and 2 standard deviation (s.d.) levels are also included. Limits are compared to predictions for scalar $\mathrm{S}_{\mathrm{uu}}$ and $\mathrm{S}_{\mathrm{dd}}$ diquarks with couplings to pairs of up and down quarks, $y_{\mathrm{uu}}$ and $y_{\mathrm{dd}}$, and to pairs of vector-like quarks, $y_{\chi}$ and $y_{\omega}$, set appropriately in order to generate a mediator width equal to 10%.

The observed 95% CL upper limits on the product of the cross section, branching fraction, and acceptance for resonant production of paired dijet resonances, X, with $\alpha_{\mathrm{true}} = M_{\mathrm{X}} / M_{\mathrm{Y}} = 0.13$ and width of the initial resonance Y equal to 10%. The corresponding expected limits and their variations at the 1 and 2 standard deviation (s.d.) levels are also included. Limits are compared to predictions for scalar $\mathrm{S}_{\mathrm{uu}}$ and $\mathrm{S}_{\mathrm{dd}}$ diquarks with couplings to pairs of up and down quarks, $y_{\mathrm{uu}}$ and $y_{\mathrm{dd}}$, and to pairs of vector-like quarks, $y_{\chi}$ and $y_{\omega}$, set appropriately in order to generate a mediator width equal to 10%.

The observed 95% CL upper limits on the product of the cross section, branching fraction, and acceptance for resonant production of paired dijet resonances, X, with $\alpha_{\mathrm{true}} = M_{\mathrm{X}} / M_{\mathrm{Y}} = 0.15$ and width of the initial resonance Y equal to 10%. The corresponding expected limits and their variations at the 1 and 2 standard deviation (s.d.) levels are also included. Limits are compared to predictions for scalar $\mathrm{S}_{\mathrm{uu}}$ and $\mathrm{S}_{\mathrm{dd}}$ diquarks with couplings to pairs of up and down quarks, $y_{\mathrm{uu}}$ and $y_{\mathrm{dd}}$, and to pairs of vector-like quarks, $y_{\chi}$ and $y_{\omega}$, set appropriately in order to generate a mediator width equal to 10%.

The observed 95% CL upper limits on the product of the cross section, branching fraction, and acceptance for resonant production of paired dijet resonances, X, with $\alpha_{\mathrm{true}} = M_{\mathrm{X}} / M_{\mathrm{Y}} = 0.17$ and width of the initial resonance Y equal to 10%. The corresponding expected limits and their variations at the 1 and 2 standard deviation (s.d.) levels are also included. Limits are compared to predictions for scalar $\mathrm{S}_{\mathrm{uu}}$ and $\mathrm{S}_{\mathrm{dd}}$ diquarks with couplings to pairs of up and down quarks, $y_{\mathrm{uu}}$ and $y_{\mathrm{dd}}$, and to pairs of vector-like quarks, $y_{\chi}$ and $y_{\omega}$, set appropriately in order to generate a mediator width equal to 10%.

The observed 95% CL upper limits on the product of the cross section, branching fraction, and acceptance for resonant production of paired dijet resonances, X, with $\alpha_{\mathrm{true}} = M_{\mathrm{X}} / M_{\mathrm{Y}} = 0.19$ and width of the initial resonance Y equal to 10%. The corresponding expected limits and their variations at the 1 and 2 standard deviation (s.d.) levels are also included. Limits are compared to predictions for scalar $\mathrm{S}_{\mathrm{uu}}$ and $\mathrm{S}_{\mathrm{dd}}$ diquarks with couplings to pairs of up and down quarks, $y_{\mathrm{uu}}$ and $y_{\mathrm{dd}}$, and to pairs of vector-like quarks, $y_{\chi}$ and $y_{\omega}$, set appropriately in order to generate a mediator width equal to 10%.

The observed 95% CL upper limits on the product of the cross section, branching fraction, and acceptance for resonant production of paired dijet resonances, X, with $\alpha_{\mathrm{true}} = M_{\mathrm{X}} / M_{\mathrm{Y}} = 0.21$ and width of the initial resonance Y equal to 10%. The corresponding expected limits and their variations at the 1 and 2 standard deviation (s.d.) levels are also included. Limits are compared to predictions for scalar $\mathrm{S}_{\mathrm{uu}}$ and $\mathrm{S}_{\mathrm{dd}}$ diquarks with couplings to pairs of up and down quarks, $y_{\mathrm{uu}}$ and $y_{\mathrm{dd}}$, and to pairs of vector-like quarks, $y_{\chi}$ and $y_{\omega}$, set appropriately in order to generate a mediator width equal to 10%.

The observed 95% CL upper limits on the product of the cross section, branching fraction, and acceptance for resonant production of paired dijet resonances, X, with $\alpha_{\mathrm{true}} = M_{\mathrm{X}} / M_{\mathrm{Y}} = 0.23$ and width of the initial resonance Y equal to 10%. The corresponding expected limits and their variations at the 1 and 2 standard deviation (s.d.) levels are also included. Limits are compared to predictions for scalar $\mathrm{S}_{\mathrm{uu}}$ and $\mathrm{S}_{\mathrm{dd}}$ diquarks with couplings to pairs of up and down quarks, $y_{\mathrm{uu}}$ and $y_{\mathrm{dd}}$, and to pairs of vector-like quarks, $y_{\chi}$ and $y_{\omega}$, set appropriately in order to generate a mediator width equal to 10%.

The observed 95% CL upper limits on the product of the cross section, branching fraction, and acceptance for resonant production of paired dijet resonances, X, with $\alpha_{\mathrm{true}} = M_{\mathrm{X}} / M_{\mathrm{Y}} = 0.27$ and width of the initial resonance Y equal to 10%. The corresponding expected limits and their variations at the 1 and 2 standard deviation (s.d.) levels are also included. Limits are compared to predictions for scalar $\mathrm{S}_{\mathrm{uu}}$ and $\mathrm{S}_{\mathrm{dd}}$ diquarks with couplings to pairs of up and down quarks, $y_{\mathrm{uu}}$ and $y_{\mathrm{dd}}$, and to pairs of vector-like quarks, $y_{\chi}$ and $y_{\omega}$, set appropriately in order to generate a mediator width equal to 10%.

The observed 95% CL upper limits on the product of the cross section, branching fraction, and acceptance for resonant production of paired dijet resonances, X, with $\alpha_{\mathrm{true}} = M_{\mathrm{X}} / M_{\mathrm{Y}} = 0.29$ and width of the initial resonance Y equal to 10%. The corresponding expected limits and their variations at the 1 and 2 standard deviation (s.d.) levels are also included. Limits are compared to predictions for scalar $\mathrm{S}_{\mathrm{uu}}$ and $\mathrm{S}_{\mathrm{dd}}$ diquarks with couplings to pairs of up and down quarks, $y_{\mathrm{uu}}$ and $y_{\mathrm{dd}}$, and to pairs of vector-like quarks, $y_{\chi}$ and $y_{\omega}$, set appropriately in order to generate a mediator width equal to 10%.

The observed 95% CL upper limits on the product of the cross section, branching fraction, and acceptance for resonant production of paired dijet resonances, X, with $\alpha_{\mathrm{true}} = M_{\mathrm{X}} / M_{\mathrm{Y}} = 0.31$ and width of the initial resonance Y equal to 10%. The corresponding expected limits and their variations at the 1 and 2 standard deviation (s.d.) levels are also included. Limits are compared to predictions for scalar $\mathrm{S}_{\mathrm{uu}}$ and $\mathrm{S}_{\mathrm{dd}}$ diquarks with couplings to pairs of up and down quarks, $y_{\mathrm{uu}}$ and $y_{\mathrm{dd}}$, and to pairs of vector-like quarks, $y_{\chi}$ and $y_{\omega}$, set appropriately in order to generate a mediator width equal to 10%.

The observed 95% CL upper limits on the product of the cross section, branching fraction, and acceptance for resonant production of paired dijet resonances, X, with $\alpha_{\mathrm{true}} = M_{\mathrm{X}} / M_{\mathrm{Y}} = 0.33$ and width of the initial resonance Y equal to 10%. The corresponding expected limits and their variations at the 1 and 2 standard deviation (s.d.) levels are also included. Limits are compared to predictions for scalar $\mathrm{S}_{\mathrm{uu}}$ and $\mathrm{S}_{\mathrm{dd}}$ diquarks with couplings to pairs of up and down quarks, $y_{\mathrm{uu}}$ and $y_{\mathrm{dd}}$, and to pairs of vector-like quarks, $y_{\chi}$ and $y_{\omega}$, set appropriately in order to generate a mediator width equal to 10%.

The observed 95% CL upper limits on the product of the cross section, branching fraction, and acceptance for resonant production of paired dijet resonances, X, with $\alpha_{\mathrm{true}} = M_{\mathrm{X}} / M_{\mathrm{Y}} = 0.42$ and width of the initial resonance Y equal to 10%. The corresponding expected limits and their variations at the 1 and 2 standard deviation (s.d.) levels are also included. Limits are compared to predictions for scalar $\mathrm{S}_{\mathrm{uu}}$ and $\mathrm{S}_{\mathrm{dd}}$ diquarks with couplings to pairs of up and down quarks, $y_{\mathrm{uu}}$ and $y_{\mathrm{dd}}$, and to pairs of vector-like quarks, $y_{\chi}$ and $y_{\omega}$, set appropriately in order to generate a mediator width equal to 10%.

The observed 95% CL upper limits on the product of the cross section, branching fraction, and acceptance for resonant production of paired dijet resonances, X, with $\alpha_{\mathrm{true}} = M_{\mathrm{X}} / M_{\mathrm{Y}} = 0.11$ and widths of the initial resonance Y equal to 1.5, 5, and 10%. Limits are compared to predictions for scalar $\mathrm{S}_{\mathrm{uu}}$ and $\mathrm{S}_{\mathrm{dd}}$ diquarks with couplings to pairs of up and down quarks, $y_{\mathrm{uu}}$ and $y_{\mathrm{dd}}$, and to pairs of vector-like quarks, $y_{\chi}$ and $y_{\omega}$, set appropriately in order to generate the corresponding widths.

The observed 95% CL upper limits on the product of the cross section, branching fraction, and acceptance for resonant production of paired dijet resonances, X, with $\alpha_{\mathrm{true}} = M_{\mathrm{X}} / M_{\mathrm{Y}} = 0.13$ and widths of the initial resonance Y equal to 1.5, 5, and 10%. Limits are compared to predictions for scalar $\mathrm{S}_{\mathrm{uu}}$ and $\mathrm{S}_{\mathrm{dd}}$ diquarks with couplings to pairs of up and down quarks, $y_{\mathrm{uu}}$ and $y_{\mathrm{dd}}$, and to pairs of vector-like quarks, $y_{\chi}$ and $y_{\omega}$, set appropriately in order to generate the corresponding widths.

The observed 95% CL upper limits on the product of the cross section, branching fraction, and acceptance for resonant production of paired dijet resonances, X, with $\alpha_{\mathrm{true}} = M_{\mathrm{X}} / M_{\mathrm{Y}} = 0.15$ and widths of the initial resonance Y equal to 1.5, 5, and 10%. Limits are compared to predictions for scalar $\mathrm{S}_{\mathrm{uu}}$ and $\mathrm{S}_{\mathrm{dd}}$ diquarks with couplings to pairs of up and down quarks, $y_{\mathrm{uu}}$ and $y_{\mathrm{dd}}$, and to pairs of vector-like quarks, $y_{\chi}$ and $y_{\omega}$, set appropriately in order to generate the corresponding widths.

The observed 95% CL upper limits on the product of the cross section, branching fraction, and acceptance for resonant production of paired dijet resonances, X, with $\alpha_{\mathrm{true}} = M_{\mathrm{X}} / M_{\mathrm{Y}} = 0.17$ and widths of the initial resonance Y equal to 1.5, 5, and 10%. Limits are compared to predictions for scalar $\mathrm{S}_{\mathrm{uu}}$ and $\mathrm{S}_{\mathrm{dd}}$ diquarks with couplings to pairs of up and down quarks, $y_{\mathrm{uu}}$ and $y_{\mathrm{dd}}$, and to pairs of vector-like quarks, $y_{\chi}$ and $y_{\omega}$, set appropriately in order to generate the corresponding widths.

The observed 95% CL upper limits on the product of the cross section, branching fraction, and acceptance for resonant production of paired dijet resonances, X, with $\alpha_{\mathrm{true}} = M_{\mathrm{X}} / M_{\mathrm{Y}} = 0.19$ and widths of the initial resonance Y equal to 1.5, 5, and 10%. Limits are compared to predictions for scalar $\mathrm{S}_{\mathrm{uu}}$ and $\mathrm{S}_{\mathrm{dd}}$ diquarks with couplings to pairs of up and down quarks, $y_{\mathrm{uu}}$ and $y_{\mathrm{dd}}$, and to pairs of vector-like quarks, $y_{\chi}$ and $y_{\omega}$, set appropriately in order to generate the corresponding widths.

The observed 95% CL upper limits on the product of the cross section, branching fraction, and acceptance for resonant production of paired dijet resonances, X, with $\alpha_{\mathrm{true}} = M_{\mathrm{X}} / M_{\mathrm{Y}} = 0.21$ and widths of the initial resonance Y equal to 1.5, 5, and 10%. Limits are compared to predictions for scalar $\mathrm{S}_{\mathrm{uu}}$ and $\mathrm{S}_{\mathrm{dd}}$ diquarks with couplings to pairs of up and down quarks, $y_{\mathrm{uu}}$ and $y_{\mathrm{dd}}$, and to pairs of vector-like quarks, $y_{\chi}$ and $y_{\omega}$, set appropriately in order to generate the corresponding widths.

The observed 95% CL upper limits on the product of the cross section, branching fraction, and acceptance for resonant production of paired dijet resonances, X, with $\alpha_{\mathrm{true}} = M_{\mathrm{X}} / M_{\mathrm{Y}} = 0.23$ and widths of the initial resonance Y equal to 1.5, 5, and 10%. Limits are compared to predictions for scalar $\mathrm{S}_{\mathrm{uu}}$ and $\mathrm{S}_{\mathrm{dd}}$ diquarks with couplings to pairs of up and down quarks, $y_{\mathrm{uu}}$ and $y_{\mathrm{dd}}$, and to pairs of vector-like quarks, $y_{\chi}$ and $y_{\omega}$, set appropriately in order to generate the corresponding widths.

The observed 95% CL upper limits on the product of the cross section, branching fraction, and acceptance for resonant production of paired dijet resonances, X, with $\alpha_{\mathrm{true}} = M_{\mathrm{X}} / M_{\mathrm{Y}} = 0.27$ and widths of the initial resonance Y equal to 1.5, 5, and 10%. Limits are compared to predictions for scalar $\mathrm{S}_{\mathrm{uu}}$ and $\mathrm{S}_{\mathrm{dd}}$ diquarks with couplings to pairs of up and down quarks, $y_{\mathrm{uu}}$ and $y_{\mathrm{dd}}$, and to pairs of vector-like quarks, $y_{\chi}$ and $y_{\omega}$, set appropriately in order to generate the corresponding widths.

The observed 95% CL upper limits on the product of the cross section, branching fraction, and acceptance for resonant production of paired dijet resonances, X, with $\alpha_{\mathrm{true}} = M_{\mathrm{X}} / M_{\mathrm{Y}} = 0.29$ and widths of the initial resonance Y equal to 1.5, 5, and 10%. Limits are compared to predictions for scalar $\mathrm{S}_{\mathrm{uu}}$ and $\mathrm{S}_{\mathrm{dd}}$ diquarks with couplings to pairs of up and down quarks, $y_{\mathrm{uu}}$ and $y_{\mathrm{dd}}$, and to pairs of vector-like quarks, $y_{\chi}$ and $y_{\omega}$, set appropriately in order to generate the corresponding widths.

The observed 95% CL upper limits on the product of the cross section, branching fraction, and acceptance for resonant production of paired dijet resonances, X, with $\alpha_{\mathrm{true}} = M_{\mathrm{X}} / M_{\mathrm{Y}} = 0.31$ and widths of the initial resonance Y equal to 1.5, 5, and 10%. Limits are compared to predictions for scalar $\mathrm{S}_{\mathrm{uu}}$ and $\mathrm{S}_{\mathrm{dd}}$ diquarks with couplings to pairs of up and down quarks, $y_{\mathrm{uu}}$ and $y_{\mathrm{dd}}$, and to pairs of vector-like quarks, $y_{\chi}$ and $y_{\omega}$, set appropriately in order to generate the corresponding widths.

The observed 95% CL upper limits on the product of the cross section, branching fraction, and acceptance for resonant production of paired dijet resonances, X, with $\alpha_{\mathrm{true}} = M_{\mathrm{X}} / M_{\mathrm{Y}} = 0.33$ and widths of the initial resonance Y equal to 1.5, 5, and 10%. Limits are compared to predictions for scalar $\mathrm{S}_{\mathrm{uu}}$ and $\mathrm{S}_{\mathrm{dd}}$ diquarks with couplings to pairs of up and down quarks, $y_{\mathrm{uu}}$ and $y_{\mathrm{dd}}$, and to pairs of vector-like quarks, $y_{\chi}$ and $y_{\omega}$, set appropriately in order to generate the corresponding widths.

The observed 95% CL upper limits on the product of the cross section, branching fraction, and acceptance for resonant production of paired dijet resonances, X, with $\alpha_{\mathrm{true}} = M_{\mathrm{X}} / M_{\mathrm{Y}} = 0.42$ and widths of the initial resonance Y equal to 1.5, 5, and 10%. Limits are compared to predictions for scalar $\mathrm{S}_{\mathrm{uu}}$ and $\mathrm{S}_{\mathrm{dd}}$ diquarks with couplings to pairs of up and down quarks, $y_{\mathrm{uu}}$ and $y_{\mathrm{dd}}$, and to pairs of vector-like quarks, $y_{\chi}$ and $y_{\omega}$, set appropriately in order to generate the corresponding widths.

Observed local $p$-value for a four-jet resonance, Y, decaying to a pair of dijet resonances, X, with $\alpha_{\mathrm{true}} = M_{\mathrm{X}}/M_{\mathrm{Y}}$ = 0.25, and various widths of Y superimposed.

Observed local $p$-value for a four-jet resonance, Y, decaying to a pair of dijet resonances, X, with $\alpha_{\mathrm{true}} = M_{\mathrm{X}}/M_{\mathrm{Y}}$ = 0.29, and various widths of Y superimposed.

The table presents the cumulative cutflow for a signal with $M_{\mathrm{S}} = 2.0$ TeV, $M_{\chi} = 0.5$ TeV and different width hypotheses ($\Gamma/M_{\mathrm{S}} =$ 1.5, 5, and 10%). Each row corresponds to the number of signal events that survive all cuts up to and including the one listed. The percentage in parentheses shows the efficiency of the current cut alone, defined as the ratio of the number of events that survive all cuts up to and including this one to the number of events that survived all previous cuts.

The table presents the cumulative cutflow for a signal with $M_{\mathrm{S}} = 5.0$ TeV, $M_{\chi} = 1.25$ TeV and different width hypotheses ($\Gamma/M_{\mathrm{S}} =$ 1.5, 5, and 10%). Each row corresponds to the number of signal events that survive all cuts up to and including the one listed. The percentage in parentheses shows the efficiency of the current cut alone, defined as the ratio of the number of events that survive all cuts up to and including this one to the number of events that survived all previous cuts.

The table presents the cumulative cutflow for a signal with $M_{\mathrm{S}} = 8.6$ TeV, $M_{\chi} = 2.15$ TeV and different width hypotheses ($\Gamma/M_{\mathrm{S}} =$ 1.5, 5, and 10%). Each row corresponds to the number of signal events that survive all cuts up to and including the one listed. The percentage in parentheses shows the efficiency of the current cut alone, defined as the ratio of the number of events that survive all cuts up to and including this one to the number of events that survived all previous cuts.

The reconstructed m$_{tb}$ distributions in data and expected background in validation region for the data taking period of 2017. Yield in each bin is divided by the corresponding bin width.

The reconstructed m$_{tb}$ distributions in data and expected background in signal region for the data taking period of 2018. Yield in each bin is divided by the corresponding bin width.

The reconstructed m$_{tb}$ distributions in data and expected background in validation region for the data taking period of 2018. Yield in each bin is divided by the corresponding bin width.

Upper limits at 95% CL on the cross section for the production of right-handed W' boson using data and backgrounds in three years combined. Theory prediction is also shown.

Upper limits at 95% CL on the cross section for the production of left-handed W' boson using data and backgrounds in three years combined. Theory prediction is also shown.

Cos(theta) distribution of jet 3 in the reduced 3-jet state.

Psi distribution of jet 3 in the reduced 3-jet state.

Normalised single-body mass distributions in the reduced 3-jet state.

Two-body energy sharing distributions, XA,of 2-jet combinations in reducing from 4-jet to 3-jet final states.

Two-body energy sharing distributions, XC,of 2-jet combinations in reducing from 5-jet to 4-jet final states.

Two-body energy sharing distribution, XE, of 2-jet combinations in reducing from 6-jet to 5-jet final states.

Two-body angular distribution, PSI(AB),of 2-jet combinations in reducing from 4-jet to 3-jet final states.

Two-body angular distribution, PSI(CD),of 2-jet combinations in reducing from 5-jet to 4-jet final states.

Two-body angular distribution, PSI(EF),of 2-jet combinations in reducing from 6-jet to 5-jet final states.

Normalised single-body mass distribution, F(A),of 2-jet combinations in reducing from 4-jet to 3-jet final states.

Normalised single-body mass distribution, F(B),of 2-jet combinations in reducing from 4-jet to 3-jet final states.

Normalised single-body mass distribution, F(C),of 2-jet combinations in reducing from 5-jet to 4-jet final states.

Normalised single-body mass distribution, F(D),of 2-jet combinations in reducing from 5-jet to 4-jet final states.

Normalised single-body mass distribution, F(E),of 2-jet combinations in reducing from 6-jet to 5-jet final states.

Normalised single-body mass distribution, F(F),of 2-jet combinations in reducing from 6-jet to 5-jet final states.

Inclusive 4-jet Dalitz X3 distribution.

Inclusive 4-jet Dalitz X4 distribution.

Inclusive 5-jet Dalitz X3 distribution.

Inclusive 5-jet Dalitz X4 distribution.

Inclusive 3-jet angular distribution in COS(THETA(3)).

Inclusive 3-jet angular distribution in CHI(3).

Inclusive 4-jet angular distribution in COS(THETA(3)).

Inclusive 4-jet angular distribution in CHI(3).

Inclusive 5-jet angular distribution in COS(THETA(3)).

Inclusive 5-jet angular distribution in CHI(3).

Single-jet mass fraction distributions in 3-jet events.

Single-body mass fraction distributions in 4-jet events.

Single-body mass fraction distributions in 5-jet events.

Two-body energy sharing variable XA in 4-jet events.

Two-body energy sharing variable XA and XC in 5-jet events.

Two-body angular distribution CHI(AB) in 4-jet events.

Two-body angular distributions CHI(AB) and CHI(CD) in 5-jet events.

Single-body mass fraction distributions FA and FB for two-body systems in 4-jet events.

Single-body mass fraction distribution FA for two-body systems in 5-jet events.

Single-body mass fraction distribution FB for two-body systems in 5-jet events.

Single-body mass fraction distribution FC for two-body systems in 5-jet events.

Single-body mass fraction distribution FD for two-body systems in 5-jet events.

Exclusive 5-jet mass distribution.

Exclusive 6-jet mass distribution.

Exclusive 3-jet mass distribution divided by the corresponding 2-jet distribution.

Exclusive 4-jet mass distribution divided by the corresponding 2-jet distribution.

Exclusive 5-jet mass distribution divided by the corresponding 2-jet distribution.

Exclusive 6-jet mass distribution divided by the corresponding 2-jet distribution.

Leading-jet angular distribution for exclusive 2-jet events.

Leading-jet angular distribution for exclusive 3-jet events.

Leading-jet angular distribution for exclusive 4-jet events.

Leading-jet angular distribution for exclusive 5-jet events.

Leading-jet angular distribution for exclusive 6-jet events.

Jet transverse momentum distrribution for exclusive 2-jet events.

Jet transverse momentum distrribution for exclusive 3-jet events.

Jet transverse momentum distrribution for exclusive 4-jet events.

Jet transverse momentum distrribution for exclusive 5-jet events.

Jet transverse momentum distrribution for exclusive 6-jet events.