Distributions of transverse momentum pTℓℓ and the related angular variable ϕη∗ of Drell–Yan lepton pairs are measured in 20.3fb-1 of proton–proton collisions at √ s = 8 TeV with the ATLAS detector at the LHC. Measurements in electron-pair and muon-pair final states are corrected for detector effects and combined. Compared to previous measurements in proton–proton collisions at √ s = 7 TeV, these new measurements benefit from a larger data sample and improved control of systematic uncertainties. Measurements are performed in bins of lepton-pair mass above, around and below the Z-boson mass peak. The data are compared to predictions from perturbative and resummed QCD calculations. For values of ϕη∗ < 1 the predictions from the Monte Carlo generator ResBos are generally consistent with the data within the theoretical uncertainties. However, at larger values of ϕη∗ this is not the case. Monte Carlo generators based on the parton-shower approach are unable to describe the data over the full range of pTℓℓ while the fixed-order prediction of Dynnlo falls below the data at high values of pTℓℓ. ResBos and the parton-shower Monte Carlo generators provide a much better description of the evolution of the ϕη∗ and pTℓℓ distributions as a function of lepton-pair mass and rapidity than the basic shape of the data.
Aad, G., Abbott, B., Abdallah, J., Abdinov, O., Aben, R., Abolins, M., et al. (2016). Measurement of the transverse momentum and ϕη∗ distributions of Drell–Yan lepton pairs in proton–proton collisions at √ s = 7 TeV with the ATLAS detector. THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS, 76(5), 291 [10.1140/epjc/s10052-016-4070-4].