Overview
- The LHC ran oxygen-oxygen and neon-neon collisions in July 2025 to test how small a collision can be and still produce plasma-like signals.
- ALICE analyzed neutral-pion production and used proton-oxygen controls to form a double ratio that suppresses cold‑nuclear‑matter effects and found a deficit consistent with parton energy loss.
- That double-ratio result survives comparison with models that omit energy loss and was reported with a 4.9 standard‑deviation significance by the ALICE team.
- ATLAS, CMS and LHCb released complementary measurements showing jet imbalances, suppressed charged‑particle yields and species-dependent patterns that strengthen the energy‑loss interpretation while each observable retains model and background sensitivities.
- Physicists say the signals are indirect evidence of QGP-like matter rather than a literal Big Bang recreation and plan more comparisons across proton, oxygen, neon, xenon and lead collisions to map how collective flow and energy loss grow with system size.