Measurements of top-quark pair to Z-boson cross-section ratios at s = 13 $$ \sqrt{s}=13 $$ , 8, 7 TeV with the ATLAS detector

Measurements of top-quark pair to Z-boson cross-section ratios at s = 13 $$ \sqrt{s}=13 $$ , 8, 7 TeV with the ATLAS detector