J/psi, psi' and Upsilon Production at Hadron Colliders: a review

TL;DR

This review traces the historical rise of heavy quarkonium physics from the J/psi discovery to modern hadroproduction studies at Tevatron and RHIC, detailing early models like the Colour-Singlet Model and Colour-Evaporation Model and the psi' anomaly that prompted fragmentation-based explanations. It dissects a suite of contemporary theoretical frameworks including NRQCD with color-octet states, k_T factorisation, Durham NNLO-like contributions, Soft-Colour Interaction, and Comover Enhancement, comparing their cross-section and polarization predictions to Tevatron and RHIC data. A central tension emerges: while several approaches can describe production rates, they struggle to reproduce observed polarization trends, challenging the universality of NRQCD matrix elements and factorisation in quarkonium hadroproduction. The review highlights the need for robust factorisation theorems and improved experimental constraints to unify the description of J/psi, psi' and Upsilon production across colliders and kinematic regimes. It also points to future directions in refining non-static effects, polarization predictions, and the role of feed-down and fragmentation in shaping observable quarkonium yields.

Abstract

We give an overview of the present status of knowledge of the production of J/psi, psi' and Upsilon in high-energy hadron collisions. We first present two early models, namely the Colour-Singlet Model (CSM) and the Colour-Evaporation Model (CEM). The first is the natural application of pQCD to quarkonium production and has been shown to fail dramatically to describe data, the second is its phenomenological counterpart and was introduced in the spirit of the quark-hadron duality in the late seventies. Then, we expose the most recent experimental measurements of J/psi, psi' and Upsilon prompt and direct production at nonzero p_T from two high-energy hadron colliders, the Tevatron and RHIC. In a third part, we review six contemporary models describing J/psi, psi' and Upsilon production at nonzero p_T.

Figures (31)

• Figure 1: Experimental status of $R$ as of July 1974 (from Ref. ?) .
• Figure 2: Spectrum and transitions of the charmonium family (Reprinted figure from Ref. ? with permission of Elsevier. Copyright (2004).).
• Figure 3: Spectrum and transitions of the bottomonium family (Reprinted figure from Ref. ?. with permission of Elsevier. Copyright (2004).).
• Figure 4: The 6 diagrams for $gg \to \!\!\ ^3S_1 g$ at LO within the CSM.
• Figure 5: Comparison between preliminary measurements of Ref. ? from CDF and the cross sections obtained by Braaten et al. for LO CSM (dashed curves) of $J/\psi$ (left) and $\psi'$ (right), as well as for CSM fragmentation contribution (solid curves). In each case, the two curves depict the extremum values obtained by varying parameters such as $m_c$ and the different scales: $\mu_R$, $\mu_F$, $\mu_{frag}$ (Reprinted figures from Ref. ? with permission of Elsevier. Copyright (1994).)