Production and polarization of prompt $J/\psi$ in the improved color evaporation model using the $k_T$-factorization approach

TL;DR

This paper presents the first $p_T$-dependent polarization calculations of prompt $J/ar{J}$ production using the improved color evaporation model with $k_T$-factorization, showing good agreement with experimental data.

Contribution

It introduces the first $p_T$-dependent polarization calculation within the improved color evaporation model for prompt $J/ar{J}$ production.

Findings

Agreement with experimental polarization data

Accurate predictions of charmonium cross sections

First $p_T$-dependent polarization analysis in this model

Abstract

We calculate the polarization of prompt $J/\psi$ production in the improved color evaporation model at leading order employing the $k_T$-factorization approach. In this paper, we present the polarization parameter $\lambda_\vartheta$ of prompt $J/\psi$ as a function of transverse momentum in $p+p$ and $p$ + A collisions to compare with data in the helicity, Collins-Soper and Gottfried-Jackson frames. We also present calculations of the charmonium production cross sections as a function of rapidity and transverse momentum. This is the first $p_T$-dependent calculation of charmonium polarization in the improved color evaporation model. We find agreement with both charmonium cross sections and polarization measurements.