Gluon TMDs and NRQCD matrix elements in $J/ψ$ production at an EIC

Alessandro Bacchetta; Daniël Boer; Cristian Pisano; Pieter Taels

Paper

Gluon TMDs and NRQCD matrix elements in $J/ψ$ production at an EIC

Abstract

In this paper we analyze azimuthal asymmetries in the processes of unpolarized and polarized

production at an Electron-Ion Collider. Apart from giving access to various unknown gluon transverse momentum distributions, we suggest to use them as a new method to extract specific color-octet NRQCD long-distance matrix elements, i.e.\

and

, whose values are still quite uncertain and for which lattice calculations are unavailable. The new method is based on combining measurements of analogous asymmetries in open heavy-quark pair production which can be performed at the same energy. To enhance the gluon contribution one can consider smaller values of

and, in order to assess the impact of small-

evolution, we perform a numerical study using the MV model as a starting input and evolve it with the JIMWLK equations.