Measurement of the transverse momentum and ϕ∗ηϕη∗ distributions of Drell–Yan lepton pairs in proton–proton collisions at s√=8s=8 TeV with the ATLAS detector

Abstract

Distributions of transverse momentum pllT and the angular variable ϕ∗η of Drell--Yan lepton pairs are measured in 20.3 fb−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 ϕ∗η<1 the predictions from the Monte Carlo generator ResBos are generally consistent with the data within the theoretical uncertainties. However, at larger values of ϕ∗η this is not generally the case. Monte Carlo generators based on the parton-shower approach are unable to describe the data over the full range of pllT and the fixed-order prediction of DYNNLO falls below the data at high values of pllT. ResBos and the parton-shower Monte Carlo generators provide a much better description of the evolution of the ϕ∗η and pllT distributions as a function of lepton-pair mass and rapidity.