$cos(2\phi_h)$ asymmetry in $J/\psi$ production in unpolarized $ep$ collision in NRQCD

TL;DR

This paper investigates the $Cos(2\phi_h)$ asymmetry in $J/\psi$ production during unpolarized electron-proton collisions, revealing how gluon polarization ratios can be studied through this asymmetry using NRQCD.

Contribution

It introduces a method to probe gluon polarization ratios via $Cos(2\phi_h)$ asymmetry in $J/\psi$ production employing NRQCD with color singlet and octet states.

Findings

The ratio of linearly polarized to unpolarized gluon distributions can be accessed through the asymmetry.

NRQCD effectively estimates $J/\psi$ production contributions from different color states.

The study provides a framework for experimental probing of gluon polarization in unpolarized protons.

Abstract

We present a recent calculation of the transverse momentum dependent gluon distributions inside unpolarised protons and show how the ratio of the linearly polarized and the unpolarized gluon distribution in the proton can be probed by looking at $Cos(2\phi_h)$ asymmetry in $J/\psi$ production in unpolarized $ep$ collision. We use NRQCD for estimating $J/\psi$ production and include contributions both from color singlet and color octet states.