Measurement of spin correlation in top-antitop quark events and search for top squark pair production in pp collisions at √s=8 TeV using the ATLAS detector

Allison, Lee and Barton, Adam and Beattie, Michael and Borissov, Guennadi and Bouhova-Thacker, Eva and Chilingarov, Alexandre and Dearnaley, William and Fox, Harald and Grimm, Kathryn and Henderson, Robert and Hughes, Gareth and Jones, Roger William Lewis and Kartvelishvili, Vakhtang and Long, Robin and Love, Peter and Maddocks, Harvey and Smizanska, Maria and Walder, James (2015) Measurement of spin correlation in top-antitop quark events and search for top squark pair production in pp collisions at √s=8  TeV using the ATLAS detector. Physical review letters, 114 (14). ISSN 1079-7114

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Abstract

A measurement of spin correlation in tt¯ production is presented using data collected with the ATLAS detector at the Large Hadron Collider in proton-proton collisions at a center-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 20.3  fb−1. The correlation between the top and antitop quark spins is extracted from dilepton tt¯ events by using the difference in the azimuthal angle between the two charged leptons in the laboratory frame. In the helicity basis the measured degree of correlation corresponds to Ahelicity=0.38±0.04, in agreement with the standard model prediction. A search is performed for pair production of top squarks with masses close to the top quark mass decaying to predominantly right-handed top quarks and a light neutralino, the lightest supersymmetric particle. Top squarks with masses between the top quark mass and 191 GeV are excluded at the 95% confidence level.

Item Type:
Journal Article
Journal or Publication Title:
Physical review letters
Additional Information:
© 2015 CERN, for the ATLAS Collaboration
Uncontrolled Keywords:
/dk/atira/pure/subjectarea/asjc/3100
Subjects:
ID Code:
74063
Deposited By:
Deposited On:
18 Jun 2015 06:00
Refereed?:
Yes
Published?:
Published
Last Modified:
12 Jul 2020 05:06