ATLAS measurements of vector boson production

ATLAS measurements of vector boson production with associated jets Productions of light and heavy-flavour jets in association with a W or a Z boson in proton-proton collisions are important processes to study QCD in multi-scale environments and the proton parton content. The cross section, differential in several kinematics variables, have been measured with the ATLAS detector in 7 TeV proton-proton collisions and compared to high-order QCD calculations and Monte Carlo simulations. The results demonstrate the need for the inclusion of high-multiplicity matrix elements in the calculations of high jet multiplicities. The ratio of (Z+jets)/(W+jets) provides a precise test of QCD due to the large cancellations of theoretical and experimental uncertainties. Measurement of W+c production cross section has a unique sensitivity to the strange-quark density, which is poorly known at low x. W or Z boson production in association with b-quark jets, on the other hand, probes the b-quark density in the proton and the b-quark production by high-order QCD processes. The experimental results are compared to leading-order and next-to-leading-order QCD calculations and various parton density predictions. --------------------------------------------------------------------------- Measurements of vector boson production in ATLAS Vector boson production in p-p collisions in LHC Run-1 has been extensively studied at the LHC. Charged and neutral current Drell-Yan cross sections are sensitive to the parton distribution functions of the proton and electroweak corrections. The measurements of the neutral current Drell-Yan process in three distinct kinematic regions, i.e. at the Z boson mass peak, below and above, are performed. The results are compared to NLO Monte Carlo simulations and to NNLO QCD predictions corrected for NLO EW effects calculated using various parameterizations of the parton distribution functions. Measurement of the transverse momentum of the Z boson is sensitive to soft resummation effects for small momentum transfers and to multiple hard jet emissions for large momentum transfers, probing QCD in a unique way. The data are used to tune next-to-leading order plus parton shower Monte Carlo simulations. An overview of these results is given.