"Grouped impact table for signal strength" of "Observation of top-quark pair production in lead-lead collisions at $\sqrt{s_\mathrm{NN}}=5.02$ TeV with the ATLAS detector"

Breakdown of relative systematic uncertainties in the measured ${t\bar{t}}$ cross-section. The quoted uncertainties are obtained by repeating the fit with a group of nuisance parameters fixed to their fitted values and subtracting in quadrature the resulting total uncertainty from the uncertainty of the complete fit. However, the total uncertainty is not the quadratic sum of the grouped impacts, as this approach neglects the correlation among the different groups.