Measurement of Wgamma and Zgamma production in proton-proton collisions at sqrt(s)=7 TeV with the ATLAS Detector

TL;DR

This paper reports measurements of W and Z boson production with associated high-energy photons in proton-proton collisions at 7 TeV, using ATLAS data, and finds agreement with Standard Model predictions.

Contribution

First measurement of Wgamma and Zgamma production cross sections at 7 TeV with detailed kinematic distributions using ATLAS data.

Findings

Measured cross sections agree with Standard Model predictions.

Provided detailed kinematic distributions of leptons and photons.

Confirmed Standard Model accuracy at 7 TeV energy scale.

Abstract

We present studies of W and Z bosons with associated high energy photons produced in pp collisions at sqrt(s)=7 TeV. The analysis uses 35 pb-1 of data collected by the ATLAS experiment in 2010. The event selection requires W and Z bosons decaying into high pT leptons (electrons or muons) and a photon with ET>15 GeV separated from the lepton(s) by a distance Delta_R(l,gamma)>0.7 in eta-phi space. A total of 95 (97) pp->e nu gamma + X (pp->mu nu gamma + X) and 25 (23) pp->e+ e- gamma + X (pp->mu+ mu- gamma + X) event candidates are selected. The kinematic distributions of the leptons and photons and the production cross sections are measured. The data are found to agree with Standard Model predictions that include next-to-leading-order O(alpha alpha_s) contributions.