Charmonium Production in Fermilab E789

TL;DR

This study measures charmonium, charm, and beauty production in high-energy proton collisions, revealing discrepancies with existing models and suggesting additional production mechanisms like color-octet processes.

Contribution

It provides detailed differential cross sections and nuclear dependence data for charmonium and heavy quark production, highlighting the need for extended theoretical models.

Findings

Charmonium cross sections exceed color-singlet model predictions

Charm and beauty production align with perturbative QCD

Nuclear dependence measurements offer new insights

Abstract

Using a sample of >10^5 J/psi to mu+mu- decays, Fermilab experiment 789 has studied production of J/psi and psi-prime in 800-GeV proton-nucleon collisions. Differential cross sections and nuclear dependences have been measured for charmonium as well as for charm and beauty production. While charm and beauty production are consistent with perturbative QCD calculations, charmonium cross sections exceed the predictions of the color-singlet model by large factors, suggesting that additional mechanisms (such as color-octet production) may play important roles. Nuclear dependences of production cross sections may offer a new tool for the detailed understanding of charmonium production.