Precise test of lepton flavour universality in W-boson decays into muons and electrons in pp collisions at s=13TeV with the ATLAS detector

The ratio of branching ratios of the W boson to muons and electrons, R-W(mu/e) = B(W -> mu nu)/B(W -> e nu), has been measured using 140 fb(-1) of pp collision data at root s = 13TeV collected with the ATLAS detector at the LHC, probing the universality o