U.S. Heavy-Ion Collision Research Suggests Protons and Neutrons May Not Be Just "Three Quarks"
The STAR Collaboration at the Relativistic Heavy Ion Collider (RHIC) at the U.S. Department of Energy's Brookhaven National Laboratory recently proposed, based on heavy-ion collision data studies, that baryons such as protons and neutrons may not be simply composed of three valence quarks, and that their baryon number may be more closely related to "baryon junctions" in the gluon field. The findings were published in the journal *Science*. In the traditional valence quark model, each quark is assigned a baryon number of 1/3, so baryons such as protons and neutrons, composed of three quarks, carry a baryon number of +1. However, this model is not a fundamental requirement of quantum chromodynamics (QCD). As early as the 1970s, alternative explanations had been proposed in the theoretical community; in 1996, Dmitri Kharzeev proposed a model suggesting that the baryon number is not necessarily carried by the quarks themselves, but may instead be concentrated at the Y-shaped junction formed by the gluon field—the "baryon junction."
2026-08-31
