Observation of Production in Collisions at with the ATLAS Detector
G. Aad (CPPM, Aix-Marseille Université, CNRS/IN2P3, Marseille, France); B. Abbott (Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, Norman, Oklahoma, USA); K. Abeling (II. Physikalisches Institut, Georg-August-Universität Göttingen, Göttingen, Germany); N. J. Abicht (Fakultät Physik, Technische Universität Dortmund, Dortmund, Germany); S. H. Abidi (Physics Department, Brookhaven National Laboratory, Upton, New York, USA); et al - Show all 2931 authors
This Letter reports the observation of production and a measurement of its cross section using of proton-proton collision data recorded at a center-of-mass energy of 13 TeV by the ATLAS detector at the Large Hadron Collider. The production cross section, with both the and bosons decaying leptonically, (, ), is measured in a fiducial phase-space region defined such that the leptons and the photon have high transverse momentum and the photon is isolated. The cross section is found to be . The corresponding standard model predicted cross section calculated at next-to-leading order in perturbative quantum chromodynamics and at leading order in the electroweak coupling constant is . The observed significance of the signal is , compared with an expected significance of .