J/psi production with NRQCD: HERA, Tevatron, RHIC and LHC

TL;DR

This paper presents a next-to-leading order calculation of J/psi production across multiple colliders within the NRQCD framework, fitting color-octet matrix elements to experimental data and demonstrating their essential role.

Contribution

The study provides a comprehensive NLO analysis of J/psi production in various experimental settings, confirming the necessity of color-octet processes in the theoretical description.

Findings

Color-octet matrix elements successfully fit multiple collider data.

The model describes p_T distributions at Tevatron, HERA, RHIC, and LHC.

Color-octet processes are essential for accurate J/psi production modeling.

Abstract

We report on our recent calculation of the inclusive direct photo- and hadroproduction of the J/psi meson at next-to-leading order within the factorization formalism of nonrelativistic QCD. We fit the color-octet (CO) long-distance matrix elements <O^(J/psi)(1S0[8])>, <O^(J/psi)(3S1[8])> and <O^(J/psi)(3P0[8])> to the transverse momentum (p_T) distributions measured by CDF at Fermilab Tevatron and by H1 at DESY HERA and show that they also successfully describe the p_T distributions from PHENIX at BNL RHIC and CMS at the CERN LHC as well as the photon-proton c.m. energy and (with worse agreement) the inelasticity distributions from H1. In all experiments, the CO processes are shown to be indispensable.