"Figure 1" of "Combination of ATLAS and CMS searches for Higgs boson pair production at $\sqrt{s} = 13$ TeV"

Expected and observed 95% CL upper limits on the total HH signal strength, defined as the ratio of the measured cross section to the sum of the ggF and VBF HH SM production cross sections, for ATLAS, CMS, and the combination of both experiments. The median expected limits on $\mu_{HH}$ are obtained under the hypotheses of no HH signal $(\mu_{HH}^{Asimov}=0)$ or assuming the presence of the SM HH signal $(\mu_{HH}^{Asimov}=1)$. The $\pm1\sigma$ and $\pm2\sigma$ bands are computed under the $\mu_{HH}^{Asimov}=0$ hypothesis.