IFLP   13074
INSTITUTO DE FISICA LA PLATA
Unidad Ejecutora - UE
artículos
Título:
Observation of spin correlation in ttˉ events from pp collisions at sqrt(s) = 7 TeV using the ATLAS detector
Autor/es:
MARTIN TRIPIANA; THE ATLAS COLLABORATION
Revista:
PHYSICAL REVIEW LETTERS
Editorial:
AMER PHYSICAL SOC
Referencias:
Lugar: New York; Año: 2012 vol. 108 p. 212001 - 212021
ISSN:
0031-9007
Resumen:
A measurement of spin correlation in tt̅ 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=0.40-0.08+0.09, in agreement with the next-to-leading-order standard model prediction. The hypothesis of zero spin correlation is excluded at 5.1 standard deviations.