RHIC Hint of QCD Critical Point

Brookhaven National Laboratory's STAR experiment measured a non‑monotonic dip in event‑by‑event transverse‑momentum fluctuations when smashing gold nuclei, a pattern inconsistent with a smooth change in behavior as collision energy varies. The dip, seen in roughly one billion collisions and reported in Physical Review Letters, is a statistically significant hint (not yet proof) of a critical point where hot quark–gluon matter changes phase. — If confirmed, locating a QCD critical point would alter our understanding of how the early universe cooled into ordinary matter and will drive theoretical work, new experiments, and likely funding and policy choices for big‑science facilities.