A precise measurement of the Z-boson double-differential transverse momentum and rapidity distributions in the full phase space of the decay leptons with the ATLAS experiment at √s = 8 TeV

This paper presents for the first time a precise measurement of the production properties of the Z boson in the full phase space of the decay leptons. The measurement is obtained from proton-proton collision data collected by the ATLAS experiment in 2012 at √s = 8 TeV at the LHC and corresponding to an integrated luminosity of 20.2 fb⁻¹. The results, based on a total of 15.3 million Z-boson decays to electron and muon pairs, extend and improve a previous measurement of the full set of angular coefficients describing Z-boson decay. The double-differential cross-section distributions in Z-boson transverse momentum p_T and rapidity y are measured in the pole region, defined as 80 < m < 100 GeV, over the range |y|< 3.6. The total uncertainty of the normalised cross-section measurements in the peak region of the p_T distribution is dominated by statistical uncertainties over the full range and increases as a function of rapidity from 0.5-1.0% for |y|< 2.0 to 2-7% at higher rapidities. The results for the rapidity-dependent transverse momentum distributions are compared to state-of-the-art QCD predictions, which combine in the best cases approximate N⁴LL resummation with N³LO fixed-order perturbative calculations. The differential rapidity distributions integrated over p_T are even more precise, with accuracies from 0.2-0.3% for |y|< 2.0 to 0.4-0.9% at higher rapidities, and are compared to fixed-order QCD predictions using the most recent parton distribution functions. The agreement between data and predictions is quite good in most cases.