Polarization of Prompt J/psi at the Tevatron

Abstract

The polarization of prompt J/psi at the Fermilab Tevatron is calculated within the nonrelativistic QCD factorization framework. The contribution from radiative decays of P-wave charmonium states decreases, but does not eliminate, the transverse polarization at large transverse momentum. The angular distribution parameter alpha for leptonic decays of the J/ψis predicted to increase from near 0 at p_T = 5 GeV to about 0.5 at p_T = 20 GeV. The prediction is consistent with measurements by the CDF Collaboration at intermediate values of p_T, but disagrees by about 3 standard deviations at the largest values of p_T measured.

Figures (1)

• Figure 1: Polarization variable $\alpha$ vs. $p_T$ for (a) direct $\psi'$ and (b) prompt $J/\psi$ compared to CDF data.