| : |
| : |
| : |
| : |
| : : Tree-level Feynman diagrams contributing to Higgs boson pair production via VBF. Diagrams~\subref{fig:feyndiagrams:cvlambda}, \subref{fig:feyndiagrams:cvcv} and \subref{fig:feyndiagrams:c2v} illustrate the non-resonant production modes scaling with $\kv\kappa_{\lambda}$, $\kappa^2_V$ and \ktv, respectively. Diagram~\subref{fig:feyndiagrams:res} illustrates the resonant production mode. |
| : : Tree-level Feynman diagrams contributing to Higgs boson pair production via VBF. Diagrams~\subref{fig:feyndiagrams:cvlambda}, \subref{fig:feyndiagrams:cvcv} and \subref{fig:feyndiagrams:c2v} illustrate the non-resonant production modes scaling with $\kv\kappa_{\lambda}$, $\kappa^2_V$ and \ktv, respectively. Diagram~\subref{fig:feyndiagrams:res} illustrates the resonant production mode. |
| : Caption not extracted |
| : Caption not extracted |
| Cumulative acceptance times efficiency at each stage of the event selection, as detailed in Section~\ref{sec:selection}. The number of events surviving the selection divided by the number of generated events is reported separately for the non-resonant signal as a function of the \ktv\ coupling modifier and for the narrow- and broad-width resonance production hypotheses as a function of the generated mass. |
| Cumulative acceptance times efficiency at each stage of the event selection, as detailed in Section~\ref{sec:selection}. The number of events surviving the selection divided by the number of generated events is reported separately for the non-resonant signal as a function of the \ktv\ coupling modifier and for the narrow- and broad-width resonance production hypotheses as a function of the generated mass. |
| : |
| : |
| : : Two-dimensional mass regions used in the analysis. The signal region is inside the inner (red) dashed curve, the validation region is outside the signal region and within the intermediate (orange) circle, and the sideband is outside the validation region and within the outer (yellow) circle. The regions are shown for \subref{fig:resolvedRegions:nores}~simulated events from the SM non-resonant $HH$ process and \subref{fig:resolvedRegions:mj}~the estimated multijet background. |
| : : Two-dimensional mass regions used in the analysis. The signal region is inside the inner (red) dashed curve, the validation region is outside the signal region and within the intermediate (orange) circle, and the sideband is outside the validation region and within the outer (yellow) circle. The regions are shown for \subref{fig:resolvedRegions:nores}~simulated events from the SM non-resonant $HH$ process and \subref{fig:resolvedRegions:mj}~the estimated multijet background. |
| Post-fit mass distribution of the $HH$ candidates in the signal region. The expected background is shown after the profile-likelihood fit to data with the background-only hypothesis; the narrow-width resonant signal at 800~\gev\ and the non-resonant signal at $\ktv=3$ are overlaid, both normalised to the corresponding observed upper limits on the cross-section. The lower panel shows the ratio of the observed data to the estimated SM background. The distribution of events is shown per mass interval corresponding to the bin width of 40~\gev, while the overflow events are included in the last bin. |
| : |
| : |
| : : Post-fit mass distribution of the $HH$ candidates in the~\subref{fig:SRmassdist} signal and~\subref{fig:addmassdist:VR} validation regions. The expected background is shown after the profile-likelihood fit to data with the background-only hypothesis; the narrow-width resonant signal at 800~\gev\ and the non-resonant signal at $\ktv=3$ are overlaid in the signal region, both normalised to the corresponding observed upper limits on the cross-section. The lower panel shows the ratio of the observed data to the estimated SM background. The distribution of events is shown per mass interval corresponding to the bin width of 40~\gev, while the overflow events are included in the last bin. |
| : : Post-fit mass distribution of the $HH$ candidates in the~\subref{fig:SRmassdist} signal and~\subref{fig:addmassdist:VR} validation regions. The expected background is shown after the profile-likelihood fit to data with the background-only hypothesis; the narrow-width resonant signal at 800~\gev\ and the non-resonant signal at $\ktv=3$ are overlaid in the signal region, both normalised to the corresponding observed upper limits on the cross-section. The lower panel shows the ratio of the observed data to the estimated SM background. The distribution of events is shown per mass interval corresponding to the bin width of 40~\gev, while the overflow events are included in the last bin. |
| : |
| : |
| : : Observed and expected 95\% CL upper limits on the production cross-section for resonant $HH$ production via VBF as a function of the mass $m_X$. The \subref{fig:CombinedLimits:narrow} narrow- and \subref{fig:CombinedLimits:broad} broad-width resonance hypotheses are presented. |
| : : Observed and expected 95\% CL upper limits on the production cross-section for resonant $HH$ production via VBF as a function of the mass $m_X$. The \subref{fig:CombinedLimits:narrow} narrow- and \subref{fig:CombinedLimits:broad} broad-width resonance hypotheses are presented. |
| Observed and expected 95\% CL upper limits on the production cross-section for non-resonant $HH$ production via VBF as a function of the di-vector-boson--di-Higgs-boson coupling modifier \ktv. The theory prediction of the cross-section as a function of \ktv\ is also shown. More details on the predicted cross-section can be found in Section~\ref{sec:samples}. |
| Observed and expected 95\% CL upper limits on the production cross-section for non-resonant $HH$ production via VBF as a function of the di-vector-boson--di-Higgs-boson coupling modifier \ktv. The theory prediction of the cross-section as a function of \ktv\ is also shown. More details on the predicted cross-section can be found in Section~\ref{sec:samples}. |