Understanding the J/psi Production Mechanism at PHENIX

TL;DR

This paper presents measurements of J/psi production at PHENIX, including transverse single-spin asymmetry and decay angular distributions, providing insights into QCD properties and the J/psi formation mechanism.

Contribution

It introduces new measurements of J/psi production mechanisms and gluon distributions in polarized protons using PHENIX data.

Findings

Decay angular distributions reveal details of J/psi production mechanisms.

Transverse SSA measurements inform on gluon distributions in polarized protons.

Results enhance understanding of QCD and J/psi formation processes.

Abstract

The large mass of the charm quark, along with the abundance of J/psi mesons observed from proton-proton collisions at PHENIX, allow for new measurements which are sensitive to basic properties of QCD. Two measurements are presented in this document: a transverse single-spin asymmetry (SSA) of J/psi production and the angular distribution for decay leptons in various reference frames. The decay distribution is directly sensitive to the J/psi production mechanism, while the transverse SSA is also sensitive to the distribution of gluons in a transversely polarized proton. Taken together, the two measurements provide a wealth of information about the formation of a J/psi meson.