EMMI Workshop: Light-ion collisions 2026

The 2025 light ion run has inspired exciting new experimental and theoretical work in the scientific communities at CERN and RHIC. The unique OO, NeNe and pO datasets collected in just over a week of beam time have triggered a wave of new analyses and studies aimed at deeper understanding of the strong nuclear force in both cold and hot regimes, spanning from the modification of cold oxygen nuclei to the onset of energy loss in the QGP. More importantly, they highlighted the LHC's abilities to collide a wide range of ion species, now unique after the RHIC shutdown. In the upcoming decade of HL-LHC running, it will be critical to leverage these capabilities to collect legacy datasets that will be used by generations of physicists for the decades after the HL-LHC shutdown, and before the future FCC-hh. Recent studies have demonstrated that a second ion injector at the HL-LHC would lead to a much more scientifically rich program with much less downtime than is currently possible. This would enable a much more efficient ion program, including both heavy and light species, as well as shorter runs for specific physics topics of great interest even outside the heavy ion community. In this contribution, we present the ATLAS perspective on these issues, which we believe will share many scientific goals with the larger HL-LHC community.