"Expected and observed limits on $\sigma_{fid}× B(X→\mu\mu)$" of "Search for dimuon resonance in the 35 to 75 GeV mass range using 140 fb$^{-1}$ of 13 TeV $pp$ collisions with the ATLAS detector"

Observed and expected 95% CL upper limits on the production fiducial cross-section times branching ratio of a narrow-width ($\Gamma=0$ GeV) resonance, as a function of the new resonance mass. Discontinuities correspond to the boundaries between different GP hyper-parameter regions. The vertical dashed lines indicate the mass points where the hyper-parameters are changed.