Bonn 2010 – scientific programme

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T: Fachverband Teilchenphysik

T 37: Top-Quarks III

T 37.8: Talk

Wednesday, March 17, 2010, 15:45–16:00, HG X

Measurement of the photon coupling to the top quark at ATLAS — I. Fleck, M. Rammes, and •O. Rosenthal — Universität Siegen

In an exotic model of right–handed quark doublets, the top quark may have an electric charge of Q_top=−4e/3 instead of the assumed Standard Model charge of Q_top=+2e/3. Such an exotic top quark t would then decay via t→ W⁻b instead of t→ W⁺b. For a limited ammount of statistics, the distinction of the two charge models can be performed by measuring the charge of the b jets and assigning correctly the b jets to their corresponding W jets. A different approach is to measure the cross section of the radiative top quark process ttγ since the coupling of photons to the top quark is directly proportional to |Q_top|². We present the most recent results of our analysis concerning this topic, based on Monte Carlo samples and a full simulation of the ATLAS detector.