"Figure 6-a (background)" of "Search for long-lived particles decaying in the CMS muon detectors in proton-proton collisions at $\sqrt{s}$ = 13 TeV"

The distributions of $N_\text{hits}$ for single CSC clusters are shown for compared to the OOT background ($t_\text{clusters} < 12.5$ ns). The OOT background is representative of the overall background shape, because the background passing all the selections described above is dominated by pileup and underlying events.