# Photon structure studied at an Electron Ion Collider

## TL;DR

The paper discusses the potential of the future Electron Ion Collider to study the partonic structure of quasi-real photons through di-jet measurements, enabling extraction of polarized and unpolarized photon parton distributions.

## Contribution

It demonstrates the feasibility of tagging resolved photon processes and measuring di-jet cross sections at an EIC, advancing photon structure research.

## Key findings

- Photon parton distributions can be extracted.
- Resolved photon processes can be effectively tagged.
- Parton flavor tagging is feasible at an EIC.

## Abstract

A future Electron Ion Collider (EIC) will be able to provide collisions of polarized electrons with protons and heavy ions over a wide range of center-of-mass energies (20 $\mathrm{GeV}$ to 140 $\mathrm{GeV}$) at an instanteous luminosity of $10^{33} - 10^{34}$ cm$^{-2}$s$^{-1}$. One of its promising physics programs is the study of the partonic structure of quasi-real photons. Measuring di-jets in quasi-real photoproduction events, one can effectively access the underlying parton dynamics of the photons. In this paper, we discuss the feasibility of tagging resolved photon processes and measuring the di-jet cross section as a function of jet transverse momentum in the range of $0.01<x_{\gamma}^{rec}<1$ at an EIC. It will be shown that both unpolarized and polarized parton distributions in the photon can be extracted, and that the flavor of the parton can be tagged at an EIC.