Mainz 2014 – scientific programme

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T: Fachverband Teilchenphysik

T 112: Top-Quarks: Assoziierte Produktion

T 112.6: Talk

Thursday, March 27, 2014, 18:00–18:15, P102

Studies of associated production of vector bosons with top-antitop pairs in the dilepton same sign channel with the ATLAS experiment at √ s=8 TeV — Kevin Kröninger, •Gvantsa Mchedlidze, Arnulf Quadt, Elizaveta Shabalina, and Tamara Vázquez Schröder — II.Physikalisches Institut of Georg-August-Universität, Göttingen, Germany

Although the top quark was discovered almost 20 years ago, some of its properties are still poorly known. Most of its couplings have not yet been directly measured. Physics beyond the Standard Model could lead to anomalous top-quark couplings. A measurement of the production of top-quark pairs in association with vector bosons is therefore a key ingredient to test the validity of the Standard Model at the TeV scale, in particular NC weak couplings of top-quark. The tt+V events are studied in the dilepton same-sign channel. One lepton can originate from associated vector boson and other from one of the two top-quarks. The benefit of searching for a same-sign dilepton event signature lies in the fact that Standard Model processes containing two prompt same-sign leptons in the final state have very small cross sections. Most backgrounds are expected to come from mis-reconstruction effects, and a data-driven estimation procedure is employed to estimate the contribution of lepton candidates within jets. The studies place a focus on the object definitions and optimal event selection.