Associated production of $J/{\psi}$ and direct photon in the NRQCD and the ICEM using the high-energy factorization

TL;DR

This paper compares NRQCD and ICEM models for associated $J/\psi$ and photon production at high energies, highlighting differences in predictions that can guide experimental discrimination and comparing to NLO collinear results.

Contribution

It introduces a high-energy factorization approach using the parton Reggeization framework to compare hadronization models for heavy quarkonium production.

Findings

NRQCD and ICEM yield significantly different cross-section predictions.

Predicted spectra can help experimentally distinguish between models.

Results slightly exceed previous NLO collinear model calculations.

Abstract

We study the associated $J/{\psi}$ and direct photon production in the high-energy factorization, as it is formulated in the parton Reggeization approach, using two different models for the hadronization of a heavy quark-antiquark pair into a heavy quarkonium, namely the non-relativistic quantum chromodynamics (NRQCD) and the improved color evaporation model (ICEM). We find essential differences in the predictions for cross-section and transverse momenta spectra obtained using the NRQCD and the ICEM, which can be used to discriminate between these models. Our prediction for cross-sections of the associated $J/{\psi}$ and direct photon production at the LHC energies slightly overestimates the results obtained early in the next-to-leading order (NLO) calculation in the collinear parton model (CPM). We predict different two-particle correlation spectra in the associated $J/{\psi}$ and direct photon production which may be of interest for experimental study.