STAR at RHIC sees hint of a critical point in nuclear matter

Physicists at Brookhaven's RHIC collided gold nuclei at 3–7.7 GeV and found an unexpected dip in transverse-momentum correlations instead of a smooth trend. The 5-sigma deviation could signal the long-sought critical point of the quark-gluon plasma transition. The findings were published Sept. 22 in Physical Review Letters.

• About 1 billion collisions analyzed at 3–7.7 GeV per nucleon pair
• Transverse-momentum correlations dip instead of changing smoothly with energy
• Deviation reaches 5 sigma, a 1-in-3.5-million statistical fluke
• Researchers call it a hint, not proof, of the critical point