Karlsruhe 2011 – wissenschaftliches Programm

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T: Fachverband Teilchenphysik

T 56: Suche nach neuer Physik I

T 56.5: Vortrag

Montag, 28. März 2011, 17:45–18:00, 30.34: 022

HEPTopTagger Performance in ATLAS — •Gregor Kasieczka, Sebastian Schätzel, and André Schöning — Physikalisches Institut, Universität Heidelberg

The large data set expected for ATLAS with the 2011 LHC run holds exciting prospects for new physics searches. Top quark finder algorithms provide an event-by-event classification which increases the signal-to-background ratio for many signals that involve top quarks in the final state.

The HEPTopTagger is a recently developed algorithm to identify and reconstruct the top quark four-momentum vector from hadronic top decay products. It utilizes the substructure of jets with a large radius (‘fat jets’). If the top quark is sufficiently boosted, the decay products will lie inside a cone that can be reconstructed as one fat jet. By unclustering the constituents of the fat jet, three distinct quark jets can be recovered. Background is rejected by imposing constraints on the reconstructed top quark and W boson masses and on the W boson helicity angle. In this presentation, the performance of the HEPTopTagger is evaluated at the level of the fully simulated calorimeter response of the ATLAS detector and compared to data recorded in the 2010 LHC run.