Münster 2017 – scientific programme

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T: Fachverband Teilchenphysik

T 4: Top Quark 1 (Produktion)

T 4.9: Talk

Monday, March 27, 2017, 18:45–19:00, JUR 4

Measurement of the ttγ production cross section in pp collisions in the dilepton channel at √s = 13 TeV with the ATLAS detector — Nello Bruscino, Julien Caudron, Markus Cristinziani, •Mazuza Ghneimat, Carlo Alberto Gottardo, Sebastian Heer, Vadim Kostyukhin, Andrea Sciandra, and Kaven Yau Wong — Physikalisches Institut, Universität Bonn

The cross section measurement of a top-quark pair in association with a photon allows a direct measurement of the top quark electromagnetic coupling. The analysis is performed at 13 TeV with the data collected by the ATLAS detector. The signal template is estimated from Monte Carlo (MC) simulation. The major background contribution is tt events with a hadron misidentified as a photon, a so-called hadron fake. The contribution from hadron fakes is estimated using a data-driven technique. The second major contribution in the dilepton channel is Z+jets events with an emission of a prompt photon, this contribution is estimated from MC simulation.

In this talk, we present a preliminary estimation of the signal and background contributions to the cross section measurement. We also present the preparation for unfolding the kinemetic distributions of the photons to recover the differential cross sections in a limited phase-space region.