# Measurement of Spin Correlation in Top-Antitop Quark Events and Search for Top Squark Pair Production in pp Collisions at $\sqrt{s}=8$ TeV Using the ATLAS Detector

Abstract : A measurement of spin correlation in $t\bar{t}$ 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 $t\bar{t}$ events by using the difference in azimuthal angle between the two charged leptons in the laboratory frame. In the helicity basis the measured degree of correlation corresponds to $A_{helicity} = 0.38 \pm 0.04$, 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.
Type de document :
Article dans une revue
Physical Review Letters, American Physical Society, 2015, 114 (14), pp.142001. 〈10.1103/PhysRevLett.114.142001〉

http://hal.in2p3.fr/in2p3-01095656
Contributeur : Emmanuelle Vernay <>
Soumis le : mardi 16 décembre 2014 - 08:14:20
Dernière modification le : mardi 22 mai 2018 - 21:48:09

### Citation

G. Aad, S. Albrand, J. Brown, J. Collot, S. Crépé-Renaudin, et al.. Measurement of Spin Correlation in Top-Antitop Quark Events and Search for Top Squark Pair Production in pp Collisions at $\sqrt{s}=8$ TeV Using the ATLAS Detector. Physical Review Letters, American Physical Society, 2015, 114 (14), pp.142001. 〈10.1103/PhysRevLett.114.142001〉. 〈in2p3-01095656〉

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