Could saturation effects be visible in a future electron-ion collider?

TL;DR

This paper investigates the potential to observe parton saturation effects in a future electron-ion collider, analyzing models consistent with existing data and emphasizing the importance of diffractive processes for detection.

Contribution

It compares saturation model predictions with collinear approaches for nuclear structure functions, highlighting the significance of diffractive observables in future experiments.

Findings

Inclusive observables are not effective for detecting saturation effects.

Diffractive processes contribute about 20% to the total cross section at high A and low Q^2.

Diffractive observables are crucial for observing parton saturation.

Abstract

We expect to observe parton saturation in a future electron - ion collider. In this letter we discuss this expectation in more detail considering two different models which are in good agreement with the existing experimental data on nuclear structure functions. In particular, we study the predictions of saturation effects in electron - ion collisions at high energies, using a generalization for nuclear targets of the b-CGC model, which describes the $ep$ HERA quite well. We estimate the total, longitudinal and charm structure functions in the dipole picture and compare them with the predictions obtained using collinear factorization and modern sets of nuclear parton distributions. Our results show that inclusive observables are not very useful in the search for saturation effects. In the small $x$ region they are very difficult to disentangle from the predictions of the collinear approaches . This happens mainly because of the large uncertainties in the latter. On the other hand, our results indicate that the contribution of diffractive processes to the total cross section is about 20 % at large A and small Q^2, allowing for a detailed study of diffractive observables. The study of diffractive processes becomes essential to observe parton saturation.