Transverse momentum dependent gluon fragmentation functions from $J/\psi\ \pi$ production at $e^+ e^-$ colliders

TL;DR

This paper proposes using back-to-back $J/$ and $\u03c0$ production at $e^+ e^-$ colliders to probe gluon transverse momentum dependent fragmentation functions, highlighting a specific azimuthal asymmetry sensitive to gluon polarization.

Contribution

It introduces a method to access gluon TMD fragmentation functions via $J/\u200b ext{--}$ and $ ext{--}$ production, assuming TMD factorization and analyzing angular distributions.

Findings

Three independent angular distributions identified.

A $ ext{cos}2\u03c6$ asymmetry sensitive to linearly polarized gluons.

Framework established at parton level for experimental exploration.

Abstract

The back-to-back $J/\psi$ and $\pi$ associated production at $e^+ e^-$ colliders is proposed to detect the gluon transverse momentum dependent(TMD) fragmentation functions. TMD factorization is assumed for this process. With spinless pion, unpolarized and linearly polarized gluon TMD fragmentation functions can be defined. It is found at parton level the hadronic tensor can be described by four structure functions. As a result, there are three independent angular distributions, of which a $\cos{2\phi}$ azimuthal asymmetry is sensitive to the linearly polarized gluon fragmentation function.