Extending QCD Frontiers with a Fixed-Target Program at the EIC

The ePIC detector at the future Electron–Ion Collider (EIC) at Brookhaven National Laboratory will be one of the most advanced experimental systems ever built to explore the structure of hadronic matter at small Bjorken-x. By revealing the dynamics of quarks and gluons inside protons and nuclei, the EIC will open new territories of Quantum Chromodynamics (QCD) that have never been experimentally accessible.

Beyond its collider mission, the EIC should be viewed as more than a single mode: it represents the future engine of nuclear physics in the United States and worldwide for the coming decades. As such, it is important to envision the EIC not only as a collider but as a multi-purpose facility that can radiate knowledge and innovation across both fundamental and applied domains.

In this presentation, I will discuss the potential of operating the EIC in a fixed-target mode, enabling proton–nucleus (p+A) and nucleus–nucleus (A+A) collisions at lower energies and larger Bjorken-x. This unique configuration would allow studies of nuclear matter across a wide range of beam energies and target species, extending QCD exploration into the low-energy regime. Such measurements are essential to build a more complete and coherent picture of QCD.

A fixed-target program at the EIC would also create a bridge between fundamental science and societal applications, from the study of cold nuclear matter, through the exploration of QCD phase transitions, to radiation studies relevant to future human space missions. By expanding the EIC’s reach beyond the collider domain, this program would help shape a new and more integrated vision for nuclear science in the decades to come.