https://doi.org/10.1140/epjc/s10052-020-7620-8
Regular Article - Theoretical Physics
Gluon TMDs and NRQCD matrix elements in 
production at an EIC
1
Dipartimento di Fisica, Università di Pavia, via Bassi 6, 27100, Pavia, Italy
2
INFN Sezione di Pavia, via Bassi 6, 27100, Pavia, Italy
3
Van Swinderen Institute for Particle Physics and Gravity, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands
4
Dipartimento di Fisica, Università di Cagliari, Cittadella Universitaria, 09042, Monserrato, CA, Italy
5
INFN Sezione di Cagliari, Cittadella Universitaria, 09042, Monserrato, CA, Italy
* e-mail: cristian.pisano@ca.infn.it
Received:
26
September
2019
Accepted:
6
January
2020
Published online:
30
January
2020
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. We also study for the first time the effects of transverse-momentum smearing in the quarkonium formation process. To enhance the gluon contribution one can consider smaller values of x and, in order to assess the impact of small-x evolution, we perform a numerical study using the MV model as a starting input and evolve it with the JIMWLK equations.
© The Author(s), 2020
