Overview
- ALICE, which posted its analysis in June 2026, measured fewer high-momentum neutral pions in oxygen–oxygen collisions and reported a double-ratio test consistent with parton energy loss at 4.9 standard deviations.
- ATLAS, CMS and LHCb produced complementary evidence through jet‑pair imbalances, suppressed charged‑particle and charm yields, and flow patterns that track the initial nuclear shape.
- The LHC ran oxygen–oxygen and neon–neon collisions at √sNN = 5.36 TeV in July 2025 to provide system sizes between proton and lead collisions for these measurements.
- ALICE used proton–oxygen collisions as a control to cancel cold‑nuclear effects, and analysts stress the energy‑loss signal is inferred from how particles emerge rather than from any direct image of a liquid droplet.
- The findings set a new experimental lower point for where strongly coupled, deconfined QCD matter shows a defining jet‑quenching signature and open a path to test whether this effect appears suddenly or grows with system size.