Abstract

Measurements of the Drell-Yan production of W and Z bosons at the LHC provide a benchmark of our understanding of perturbative QCD and probe the proton structure in a unique way. The ATLAS collaboration has performed new high precision measurements at a center-of-mass energy of 7 TeV. The measurements are performed for W+, W- and Z bosons integrated and as a function of the boson or lepton rapidity and the Z mass. Unprecedented precision is reached and strong constraints on Parton Distribution Functions, in particular the strange density are found. Z boson cross sections are also measured at center-of-mass energies of 8 TeV and 13 TeV, and cross-section ratios to the top-quark pair production have been derived. This ratio measurement leads to a cancellation of systematic effects and allows for a high precision comparison to the theory predictions. The production of jets in association with vector bosons is a further important process to study perturbative QCD in a multi-scale environment. The ATLAS collaboration has performed new measurements of Z boson plus jets cross sections, differential in several kinematic variables, in proton-proton collision data taken at a center-of-mass energy of 13 TeV. The measurements are compared to state-of-the art theory predictions. They are sensitive to higher-order pQCD effects, probe flavour and mass schemes and can be used to constrain the proton structure. In addition, a new measurement of the splitting scales of the kt jet-clustering algorithm for final states containing a Z boson candidate at a center-of-mass energy of 8 TeV is presented.

Highlights

  • The production of W and Z bosons via the Drell-Yan process is widely studied at the LHC experiments with proton-proton collision, including the ATLAS experiment [1]

  • A selection of seven of the most recent ATLAS results on vector boson physics will be presented: W and Z boson production cross section at 7 TeV [2] and 13 TeV [3]; ratio of ttover Z boson production cross section at 7, 8 and 13 TeV [4]; Z+jets production cross section at 13 TeV [5]; triple differential Z boson cross section at 8 TeV [6]; angular coefficients of Z boson leptons [7] and splitting scales of anti-kt algorithm clustered jets [8], both measured with 8 TeV data

  • The ATLAS result is compared with predictions obtained adopting different physics analyses.https://doi.org/10.1051/epjconf/201817203001Parton Distribution Functions (PDFs); in all cases, the predicted cross section ratio values are higher than those measured in data, clearly pointing out the need for improvements in the description of the proton structure

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Summary

Introduction

The production of W and Z bosons via the Drell-Yan process is widely studied at the LHC experiments with proton-proton collision, including the ATLAS experiment [1]. Those processes have a clear signature (especially in the lepton decay channels: Z → ll and W → lν) and are characterized by small background contamination. A selection of seven of the most recent ATLAS results on vector boson physics will be presented: W and Z boson production cross section at 7 TeV [2] and 13 TeV [3]; ratio of ttover Z boson production cross section at 7, 8 and 13 TeV [4]; Z+jets production cross section at 13 TeV [5]; triple differential Z boson cross section at 8 TeV [6]; angular coefficients of Z boson leptons [7] and splitting scales of anti-kt algorithm clustered jets [8], both measured with 8 TeV data

W and Z boson cross section at 7 TeV
W and Z boson cross section at 13 TeV
Triple differential Z boson cross section at 8 TeV
Drell-Yan lepton angular correlations
Anti-kt jet splitting scales
Findings
Conclusion
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