25-30 September 2011
Sant Feliu de Guixols, Spain
Europe/Madrid timezone

The measurement of the top quark charge in the ATLAS experiment

Not scheduled
Sant Feliu de Guixols, Spain

Sant Feliu de Guixols, Spain

Speaker

Pavol Federic (Bratislava University)

Description

We present a measurement of the electric charge of the top quark in the lepton+jets final states using 0.70/fb of data accumulated in the ATLAS experiment at a center of mass energy of 7 TeV. The top quark charge measurement is based on reconstructing the charges of the top quark decay products. While we determined the charge of the W boson through its leptonic decay, the b-quark charge is not directly measurable. However we use two methods to determine b-quark charge. The first is based on a correlation between the charge of the b-quark and a weighted sum of the charges of the hadrons produced in the b-quark hadronisation process (track charge weighting technique). The second method uses semileptonic B-hadrons decays. In this case the sign of the lepton arising from the semileptonic decay defines the sign of the b-quark (soft lepton technique). The results were compared with expectations for the Standard Model top quark and for a "top-like" quark with an exotic charge of -4/3e. The exotic scenario is excluded at more than five standard deviations confidence level using both methods of determining the b-jet charge.

Primary authors

Pavol Federic (Bratislava University) Zdenek Dolezal (Charles University (CZ))

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