Observation of Spin Correlation in tt¯ Events from pp Collisions at s√=7 TeV Using the ATLAS Detector

Barton, Adam and Borissov, Guennadi and Bouhova-Thacker, Eva and Brodbeck, Timothy and Chilingarov, Alexandre and Davidson, Ruth and de Mora, Lee and Dearnaley, William and Fox, Harald and Henderson, Robert and Hughes, Gareth and Jones, Roger William Lewis and Kartvelishvili, Vakhtang and Long, Robin and Love, Peter and Ratoff, Peter and Smizanska, Maria and Walder, James (2012) Observation of Spin Correlation in tt¯ Events from pp Collisions at s√=7  TeV Using the ATLAS Detector. Physical review letters, 108 (21). ISSN 1079-7114

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Abstract

A measurement of spin correlation in tt¯ production is reported using data collected with the ATLAS detector at the LHC, corresponding to an integrated luminosity of 2.1  fb−1. Candidate events are selected in the dilepton topology with large missing transverse energy and at least two jets. The difference in azimuthal angle between the two charged leptons in the laboratory frame is used to extract the correlation between the top and antitop quark spins. In the helicity basis the measured degree of correlation corresponds to Ahelicity=0.40+0.09−0.08, in agreement with the next-to-leading-order standard model prediction. The hypothesis of zero spin correlation is excluded at 5.1 standard deviations.

Item Type:
Journal Article
Journal or Publication Title:
Physical review letters
Additional Information:
Published by the American Physical Society under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. © 2012 CERN, for the ATLAS Collaboration
Uncontrolled Keywords:
/dk/atira/pure/subjectarea/asjc/3100
Subjects:
ID Code:
68155
Deposited By:
Deposited On:
19 Dec 2013 16:10
Refereed?:
Yes
Published?:
Published
Last Modified:
29 Mar 2020 03:27