Münster 2017 – wissenschaftliches Programm

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T: Fachverband Teilchenphysik

T 51: Top Quark 3 (Produktion)

T 51.1: Vortrag

Dienstag, 28. März 2017, 16:45–17:00, JUR 4

Single top production in association with a Z boson with ATLAS — •Irina Cioară and Ian C. Brock — Physikalisches Institut, University of Bonn

The 13 TeV data collected by the ATLAS collaboration in Run2 is used to investigate the electroweak process in which a Z boson is radiated in the t-channel single top-quark production (tZq channel). This has the potential to constrain the top-quark to Z boson coupling, and is an irreducible background for flavour changing neutral current decays of the top quark.

The trilepton decay topology of this process produces one jet originating from a b quark, three charged leptons with high transverse momentum (including an opposite sign, same flavour pair), one light-quark jet that tends to be in the forward direction and one neutrino. Despite the very low branching fraction, this channel is chosen because it has the best signal to background ratio and hence, the best potential for discovery.

The analysis is performed using the full dataset collected with the ATLAS detector in 2015 and 2016 and the strategy includes using a neural network for separating signal and background and performing a binned likelihood fit in order to extract the measured cross-section. A cut-and-count approach is also studied.