Measurement of the W+W- Production Cross Section in Proton-Proton Collisions at sqrt(s) = 7 TeV with the ATLAS Detector

This note reports on a measurement of the W+W− production cross section in pp collisions at sqrt(s) = 7 TeV. The W+W− leptonic decay channels are analyzed using data corresponding to 4.7/fb of integrated luminosity collected by the ATLAS detector during 2011 at the CERN Large Hadron Collider. With 1524 observed W+W− candidate events and an estimated background of 531 ± 51 events, the measured W+W− production cross section is 53.4 ± 2.1 (stat) ± 4.5 (syst) ± 2.1 (lumi) pb, to be compared with the Standard Model NLO prediction of 45.1 ± 2.8 pb.