Small-x TMD distributions: JIMWLK evolution and the Gaussian truncation
Abstract
We extend the systematic study of small-x Transverse Momentum Dependent (TMD) distributions, initiated in [Cougoulic:2026drr], by including the energy evolution. We use the JIMWLK evolution equation to study the energy dependence of three distributions in the quark-gluon sector, ℱqg, and seven distributions in the gluon-gluon sector, ℱgg. The initial conditions are provided by the McLerran-Venugopalan model. We study these TMD distributions in position space and with Nc = 3 fixed. We then compare these results to the Gaussian truncation of the Balitsky hierarchy. Although the Gaussian truncation worked very well for the TMD distributions at the initial condition, now we identify some cases where the Gaussian truncation provides a reasonably good description, but in the majority of cases it fails to fully reproduce numerical data. Using the fixed representation building blocks, Ωagω, we are able to partially explain the outcomes. This work constitutes the next step with the goal of understanding the interplays between the large-Nc limit and Gaussian truncation as well as the BK/JIMWLK evolution equations for phenomenologically relevant observables.
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BibTeX
@misc{cougoulic2026smallx,
title = {{Small-x TMD distributions: JIMWLK evolution and the Gaussian truncation}},
author = {Florian Cougoulic and Piotr Korcyl},
howpublished = {arXiv},
year = {2026},
month = aug,
doi = {10.48550/arxiv.2608.30687},
eprint = {2608.30687},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2608.30687},
}
RIS
TY - UNPB
TI - Small-x TMD distributions: JIMWLK evolution and the Gaussian truncation
AU - Florian Cougoulic
AU - Piotr Korcyl
PY - 2026
DA - 2026/08/31
PB - arXiv
DO - 10.48550/arxiv.2608.30687
UR - https://arxiv.org/abs/2608.30687
AB - We extend the systematic study of small-x Transverse Momentum Dependent (TMD) distributions, initiated in [Cougoulic:2026drr], by including the energy evolution. We use the JIMWLK evolution equation to study the energy dependence of three distributions in the quark-gluon sector, ℱ_qg, and seven distributions in the gluon-gluon sector, ℱ_gg. The initial conditions are provided by the McLerran-Venugopalan model. We study these TMD distributions in position space and with N_c = 3 fixed. We then compare these results to the Gaussian truncation of the Balitsky hierarchy. Although the Gaussian truncation worked very well for the TMD distributions at the initial condition, now we identify some cases where the Gaussian truncation provides a reasonably good description, but in the majority of cases it fails to fully reproduce numerical data. Using the fixed representation building blocks, Ω_ag^ω, we are able to partially explain the outcomes. This work constitutes the next step with the goal of understanding the interplays between the large-N_c limit and Gaussian truncation as well as the BK/JIMWLK evolution equations for phenomenologically relevant observables.
ER -