Wuppertal 2015 – scientific programme

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T: Fachverband Teilchenphysik

T 20: Top: Boosted top, Resonanzen

T 20.6: Talk

Monday, March 9, 2015, 18:05–18:20, L.10.31 (HS 10)

Measurement of the differential cross-section of highly boosted top quarks as a function of their transverse momentum using the ATLAS detector in √s = 8 TeV proton-proton collisions — •Ofir Gabizon for the ATLAS collaboration — Bergische Universität Wuppertal, Wuppertal, Germany

The differential cross-section for boosted top quark pair production is measured with 20.3 fb⁻¹ of proton-proton collisions at a center-of-mass energy of 8 TeV. The measurement is performed for tt events in the lepton+jets channel, where the hadronically decaying top quark has a transverse momentum above 300 GeV, and is reported as a function of the hadronically decaying top quark transverse momentum. Jet substructure techniques are employed to identify top quarks, which are reconstructed with an anti-kt jet with radius parameter R=1.0. The observed yield is corrected for detector effects to obtain a cross-section at particle-level in a fiducial region close to the event selection. A parton-level cross-section extrapolated to the full phase-space is also reported for top quarks with transverse momentum above 300 GeV. The predictions of next-to-leading-order and leading-order matrix element plus parton shower Monte Carlo generators are found to generally overestimate the measured cross-sections.