Coulomb corrections to DIS off heavy nuclei

TL;DR

This paper calculates Coulomb corrections to deep inelastic scattering (DIS) off heavy nuclei, revealing significant effects that violate geometric scaling and are crucial for understanding nuclear structure at low x in future collider experiments.

Contribution

It introduces the first detailed computation of Coulomb corrections to DIS cross sections, highlighting their impact on geometric scaling and their magnitude in heavy nuclei.

Findings

Coulomb corrections can reach 20-40% in cross sections for heavy nuclei.

These corrections violate geometric scaling across a wide range of photon virtualities.

Coulomb effects are weakly dependent on the Bjorken x variable.

Abstract

An essential part of experimental program at the future Electron Ion Collider is the study of the nuclear structure and dynamics at low $x$. DIS at low $x$ is characterized by large longitudinal coherence length that by far exceeds radii of heavy nuclei. The coherent behavior is essential feature of the nuclear matter at low $x$. This pertains not only to the strong interactions, but also to electromagnetic ones. Coherent interactions of a projectile with nucleons in a heavy nucleus are characterized by parameters $\alpha_s^2 A^{1/3}\sim 1$ and $\alpha Z\sim 1 $ in strong and electromagnetic interactions respectively. Contributions exhibiting non-trivial dependence on $\alpha Z$ are called the Coulomb corrections. We compute the Coulomb corrections to the cross sections of the semi-inclusive and diffractive DIS. We show that they violate the geometric scaling in a wide range of photon virtualities and is weakly $x$-independent. In heavy nuclei at low $Q^2$ the Coulomb correction to the total and diffractive cross sections is about 20% and 40% correspondingly.