"Figure 9a" of "Search for vector-like leptons coupling to first- and second-generation Standard Model leptons in $pp$ collisions at $\sqrt{s}=13$ TeV with the ATLAS detector"

Combined observed and expected limits at 95% CL for the (a) VLLeS, (b) VLLeD, (c) VLLμS, and (d) VLLμD models, as a function of the mass of the VLL. The inner and outer bands around the expected limit are the ± 1 σ and ± 2 σ variations including all uncertainties, respectively. The theoretical prediction for the signal production cross-section is also shown as a red solid line. Expected limits on the signal cross-section from the individual channels are shown in dashed lines for 2ℓOS (long-dashed), 3ℓ (short-dashed), and 4ℓ (dot-dashed).