Münster 2017 – wissenschaftliches Programm

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T: Fachverband Teilchenphysik

T 51: Top Quark 3 (Produktion)

T 51.5: Vortrag

Dienstag, 28. März 2017, 17:45–18:00, JUR 4

Associated single top quark+ Z boson production in a dilepton final state at ATLAS — Ian Brock, Irina Cioară, and •Dorothee Wohlleben — Physikalisches Institut, University of Bonn

The investigation of the associated single top quark+ Z boson production in a dilepton final state at ATLAS at 13TeV is interesting, because it has the potential of giving further insight into the top quark- Z boson coupling. It is also an important background in analyses investigating flavor changing neutral current decays of the top quark.

There are in total four different final states that occur in tZq production, depending on the combination of the t quark and Z boson decay. In case of the dilepton channel, the Z boson decays into two leptons while the t quark decays into a b quark and a W boson. The W boson in turn decays into two quarks.

The dominant background for the dilepton channel is the Z boson+jets, having a very similar final state as the tZq events. Because of this and the very high cross-section of the background processes compared to tZq, the selection has to be optimized in order to increase the signal to background ratio. Additionally, the sensitivity of a tZq analysis in this channel is evaluated after using a neural network in order to improve the separation between the signal and background events.