2012/06/25 by J. Erdmann, Johannes Erdmann, Erdmann, Johannes
Physics and Astronomy · #FOS: Physical sciences #High Energy Physics - Experiment (hep-ex) #High-Energy Particle Collisions Research #Particle Detector Development and Performance #Particle physics theoretical and experimental studies #hep-ex
paper · pdf · doi:10.48550/arxiv.1206.5696
139 pages, thesis
arxiv created 2012/06/25 · openalex publication_date 2012/06/25 · arxiv updated 2012/06/26 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
A first measurement of the ttgamma cross section in pp collisions at the LHC using 1.04 fb-1 of data taken with the ATLAS detector is presented. A total of 122 candidate events were identified in the single electron and single muon channels. The contributions from background processes with prompt photons, and with electrons or hadrons misidentified as photons were estimated reducing the dependence on simulations by the use of data-driven techniques. The resulting cross section times branching ratio into the single lepton and dilepton decay channels for photons with pt > 8 GeV reads σttgamma * BR = 1.9 pm 0.5 (stat.) pm 0.8 (syst.) pm 0.1 (lumi.) pb, which is consistent with the Standard Model expectation from theoretical calculations. The significance of the ttgamma signal was estimated to 2.5 σ.