Two Key Day-One Observables in Electron-Nucleus Collisions at the Upcoming Electron-Ion Collider and Their Implications for Baryon Number Carrier Investigations

Abstract

In high-energy collisions, the transverse momentum and rapidity (or pseudorapidity) distributions of charged particles are two key day-one observables related to characterize the collective dynamics of the produced system, and the upcoming Electron-Ion Collider (EIC) is no exception. While these distributions are sensitive to collective behavior, previous studies have demonstrated that they also exhibit distinct features at different energies that are intrinsically correlated with the nature of baryon number carriers: whether they are valence quarks or gluon junctions. Across the energy range from a few GeV to tens of GeV, extending to hundreds of GeV and even the TeV scale, baryon number carriers may undergo a partial or complete transition from valence quarks to gluon junctions. Understanding this transition is essential for a comprehensive picture of particle production, which in turn provides a crucial baseline for disentangling genuine collective effects in future EIC experiments.

arXiv comment21 pages, 9 figures. The title has been changed