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 5GeV/c. The analysis is performed using a data sample with an integrated luminosity of about 800pb-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 30GeV/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.
Publication Source (Journal or Book title)
Physical Review Letters
Abulencia, A., Adelman, J., Affolder, T., Akimoto, T., Albrow, M., Amerio, S., Amidei, D., Anastassov, A., Anikeev, K., Annovi, A., Antos, J., Aoki, M., Apollinari, G., Arisawa, T., Artikov, A., Ashmanskas, W., Attal, A., Aurisano, A., Azfar, F., Azzi-Bacchetta, P., Azzurri, P., Bacchetta, N., Badgett, W., Barbaro-Galtieri, A., Barnes, V., Barnett, B., Baroiant, S., & Bartsch, V. (2007). Polarizations of J/ψ and ψ(2S) mesons produced in pp̄ collisions at s=1.96TeV. Physical Review Letters, 99 (13) https://doi.org/10.1103/PhysRevLett.99.132001