Dresden 2013 – wissenschaftliches Programm

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T: Fachverband Teilchenphysik

T 35: Top-Quarks 3

T 35.7: Vortrag

Montag, 4. März 2013, 18:15–18:30, HSZ-02

Observables to identify leptonically decaying top quarks at high energies in ATLAS — •Madalina Stanescu-Bellu — DESY

Searching for new physics in ttbar events requires efficient reconstruction of the top quarks, over a large range in the invariant ttbar mass. For tops produced at low energies, the decay products are well separated. The tops produced at high energies are boosted and their decay products are collimated in a narrow cone. The main challenge is to distinguish the top quarks from SM background, such as W+jets. For leptonically decaying tops (l+b+neutrino), this is done by a lepton close to a b-jet. The topic of this study is the leptonically decaying boosted tops and the observables to distinguish the lepton from the close distanced b(c) jet. Such observables are the invariant mass of the jet, the fraction of the lepton momentum from the total jet momentum, and the relative isolation. These observables are compared for SM ttbar decays and ttbar pairs originating from a hypothetical heavy particle Z'.