The Emerging QCD Frontier: The Electron Ion Collider

TL;DR

The paper advocates for an Electron-Ion Collider to explore gluon properties in QCD, highlighting its potential to uncover saturation physics and collective gluon behavior beyond current experimental capabilities.

Contribution

It presents a compelling physics case for e+A collisions at an EIC and discusses the design status of such a facility.

Findings

Hints of saturated gluon densities from HERA and RHIC data

Saturation physics impacts heavy-ion collisions at LHC

EIC will enable exploration of dense gluon assemblies

Abstract

The self-interactions of gluons determine all the unique features of QCD and lead to a dominant abundance of gluons inside matter already at moderate $x$. Despite their dominant role, the properties of gluons remain largely unexplored. Tantalizing hints of saturated gluon densities have been found in $e$+p collisions at HERA, and in d+Au and Au+Au collisions at RHIC. Saturation physics will have a profound influence on heavy-ion collisions at the LHC. But unveiling the collective behavior of dense assemblies of gluons under conditions where their self-interactions dominate will require an Electron-Ion Collider (EIC): a new facility with capabilities well beyond those In this paper I outline the compelling physics case for $e$+A collisions at an EIC and discuss briefly the status of machine design concepts. of any existing accelerator.