2011/09/30 by T. Golling, Golling, Tobias
Computer Science · Physics and Astronomy · #Computational Physics and Python Applications #FOS: Physical sciences #High Energy Physics - Experiment (hep-ex) #High-Energy Particle Collisions Research #Particle physics theoretical and experimental studies
paper · pdf · doi:10.48550/arxiv.1109.6734
openalex publication_date 2011/09/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Two searches for new phenomena involving top quarks are presented: a search for a top partner in ttbar events with large missing transverse momentum, and a search for ttbar resonances in proton-proton collisions at a center-of-mass energy of 7 TeV. The measurements are based on 35 pb-1 and 200 pb-1 of data collected with the ATLAS detector at the LHC in 2010 and 2011, respectively. No evidence for a signal is observed. The first limits from the LHC are established on the mass of a top partner, excluding a mass of 275 GeV for a neutral particle mass less than 50 GeV and a mass of 300 GeV for a neutral particle mass less than 10 GeV. Using the reconstructed ttbar mass spectrum, limits are set on the production cross-section times branching ratio to ttbar for narrow and wide resonances. For narrow Z' models, the observed 95% C.L. limits range from approximately 38 pb to 3.2 pb for masses going from mZ' = 500 GeV to mZ' = 1300 GeV. In Randall-Sundrum models, Kaluza-Klein gluons with masses below 650 GeV are excluded at 95% C.L.