"Figure 15a" of "Search for new particles decaying into top quark-antiquark pairs in proton-proton collisions at $\sqrt{s}$ = 13 TeV"

Expected and observed upper limits at 95% CL on the product of the production cross section and branching fraction as a function of the resonance mass. The limits are shown for a Z' boson with a relative width of 1%. The expected combined upper limit on the signal strength times branching ratio, together with the 68% and 95% uncertainty bands, the expected and observed limits from the individual channels, and the corresponding theory prediction are shown.