Fig. 5.

Expected and observed 95% CL limits on $\mathcal{B}(\mathrm{H}\to \mathrm{X}\mathrm{X})\mathcal{B}{(\mathrm{X}\to \mathrm{\mu }\mathrm{\mu })}^2$ assuming $\mathrm{X}$ decays to dimuons only, $\mathcal{B}(\mathrm{H}\to \mathrm{X}\mathrm{X})\mathcal{B}{(\mathrm{X}\to \mathrm{e}\mathrm{e})}^2$ assuming $\mathrm{X}$ decays to dielectrons only, and $\mathcal{B}(\mathrm{H}\to \mathrm{X}\mathrm{X})\mathcal{B}{(\mathrm{X}\to \mathrm{e}\mathrm{e}\text{or}\mu \mu )}^2$ assuming a flavor symmetric decay of $\mathrm{X}$ to dimuons and dielectrons. The dashed black curve is the expected upper limit, with one and two standard-deviation bands shown in green and yellow, respectively. The solid black curve is the observed upper limit. The red curve represents the theoretical cross section for the signal process $\mathrm{H}\to \mathrm{X}\mathrm{X}\to 4\ell$. The discontinuity at 12$\text{GeV}$ in uncertainty is due to the switch from experimental to theoretical uncertainty estimates of $\mathcal{B}({\mathrm{Z}}_{\mathrm{D}}\to \mathrm{e}\mathrm{e}\text{or}\mathrm{\mu }\mathrm{\mu })$, as described in Ref. [7]. The symbol $\kappa$ is the Higgs-mixing parameter. The grey band corresponds to the excluded region around the $\mathrm{b}\overline{\mathrm{b}}$ bound states of ${\rm Y}$