# Heavy quarkonium photoproduction in ultrarelativistic heavy ion collisions

## TL;DR

This paper uses NRQCD to calculate heavy quarkonium production in ultrarelativistic heavy ion collisions, showing that experimental data at LHC can be explained by this formalism with significant contributions from photoproduction and fragmentation processes.

## Contribution

It provides a detailed calculation of heavy quarkonium production via photoproduction and fragmentation in heavy ion collisions using NRQCD, aligning with LHC data.

## Key findings

- NRQCD describes existing LHC heavy quarkonium data well
- Photoproduction and fragmentation are significant in p-p and Pb-Pb collisions
- Color-singlet and color-octet matrix elements dominate the production

## Abstract

Based on the factorization formalism of nonrelativistic quantum chromodynamics (NRQCD), we calculate the production cross section for the charmonium and the bottomonium produced by the hard photoproduction processes and fragmentation processes in relativistic heavy ion collisions. It is shown that the existing experimental data on heavy quarkonium production at the Large Hadron Collider (LHC) can be described in the framework of the NRQCD formalism, and the phenomenological values of matrix elements for color-singlet and color-octet components give the main contribution. The numerical results of photoproduction processes and fragmentation processes for the heavy quarkonium production become prominent in p-p collisions and Pb-Pb collisions at LHC energies.