2003/06/30 by B. L. Ioffe, B.L. Ioffe, D. E. Kharzeev +1 · 1 citation
Physics and Astronomy · #High-Energy Particle Collisions Research #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions #hep-ph
paper · pdf · doi:10.1103/physrevc.68.061902
published as Phys.Rev. C68 (2003) 061902 · 4 pages, no figures
arxiv created 2003/07/02 · openalex publication_date 2003/12/31 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The polarization of quarkonium states produced in hadron collisions exhibits strong nonperturbative effects---for example, at small transverse momentum pt charmonia appear unpolarized, in sharp contradiction to the predictions of perturbation theory. The quark-gluon plasma is expected to screen away the nonperturbative physics; therefore those quarkonia which escape from the plasma should possess polarization as predicted by perturbative QCD. We estimate the expected J∕\ensuremathψ polarization at small pt, and find that it translates into the asymmetry of the e+e^\ensuremath-(\ensuremathμ+\ensuremathμ^\ensuremath-) angular distribution W(\ensuremathθ)\ensuremath∼1+\ensuremathαcos2\ensuremathθ, with \ensuremathα\ensuremath≃0.35--0.4.