# Polarized Heavy Quarkonium Production in the Color Evaporation Model

## TL;DR

This paper investigates the polarization characteristics of heavy quarkonium production in proton-proton collisions using the color evaporation model, revealing energy and rapidity-dependent polarization patterns.

## Contribution

It provides the first analysis of polarized heavy quarkonium production within the color evaporation model at leading order, highlighting polarization behaviors across energies and rapidities.

## Key findings

- Charmonium and bottomonium are longitudinally polarized at high energies.
- Quarkonium polarization shifts from longitudinal to transverse at forward rapidities.
- Polarization patterns depend on energy and rapidity, varying from longitudinal to transverse.

## Abstract

We explore polarized heavy quarkonium production using the color evaporation model at leading order. We present the polarized to total yield ratio as a function of center of mass energy and rapidity in $p+p$ collisions. At energies far above the $Q \overline Q$ production threshold, we find charmonium and bottomonium production to be longitudinally polarized ($J_z=0$). The quarkonium states are also longitudinally polarized at central rapidity, becoming transversely polarized ($J_z=\pm1$) at the most forward rapidities.