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Phys. Rev. Lett. 99, 132001 (2007) [7 pages]

Polarizations of J/ψ and ψ(2S) Mesons Produced in pp̅ Collisions at s=1.96  TeV

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A. Abulencia et al. CDF Collaboration
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Received 3 April 2007; published 26 September 2007

We have measured the polarizations of J/ψ and ψ(2S) mesons as functions of their transverse momentum pT when they are produced promptly in the rapidity range |y|<0.6 with pT≥5  GeV/c. The analysis is performed using a data sample with an integrated luminosity of about 800  pb-1 collected by the CDF II detector. For both vector mesons, we find that the polarizations become increasingly longitudinal as pT increases from 5 to 30  GeV/c. These results are compared to the predictions of nonrelativistic quantum chromodynamics and other contemporary models. The effective polarizations of J/ψ and ψ(2S) mesons from B-hadron decays are also reported.

© 2007 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevLett.99.132001
DOI:
10.1103/PhysRevLett.99.132001
PACS:
13.88.+e, 13.20.Gd, 14.40.Lb