# Gluons and sea quarks in the proton at low scales

## TL;DR

This paper investigates the behavior of gluons and sea quarks in the proton at low energy scales, revealing that current parton distribution fits cannot be explained solely by perturbative QCD evolution.

## Contribution

It demonstrates that existing parton density fits are incompatible with purely perturbative generation of gluons and sea quarks at low scales, challenging standard assumptions.

## Key findings

- Current PDFs cannot be generated solely by perturbative evolution.
- Parton distributions at low scales require non-perturbative contributions.
- Analysis confirms previous findings about non-perturbative effects in proton structure.

## Abstract

We study the evolution of parton distributions down to low scales by considering several of their Mellin moments. For the initial conditions, we use a broad array of current parton density fits. Confirming earlier findings in the literature, we conclude that current determinations of parton distributions are incompatible with the idea that gluon or antiquark densities are generated by purely perturbative radiation as it is encoded in the DGLAP evolution equations.