Measurements of top-quark pair to Z-boson cross-section ratios at root s=13, 8, 7 TeV with the ATLAS detector - Terron Cuadrado, Juan; Glasman Kuguel, Claudia Beatriz; Peso Malagon, Jose Del; Cueto Gomez, Ana Rosario; Calvente Lopez, Sergio; Barreiro Alonso, Fernando (Journal Of High Energy Physics, 2017)