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Keyword：quantum chromodynamics
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
After 25 Years, the Muon Wobble Puzzle Sees Key New Progress in Physics
For 25 years, precise measurements of how muons wobble in a magnetic field have been a major puzzle in particle physics. Early experiments showed a discrepancy between the measured value of the muon's g-factor and theoretical predictions, a difference once seen as a possible hint of unknown particles. Recent new theoretical calculations and experimental analyses have brought a new twist to this puzzle. The muon is a heavier cousin of the electron that precesses like a tiny magnet in a magnetic field. Its extra wobble is quantified by the muon g-2 coefficient. According to quantum theory, known particles and interactions influence this coefficient through fleeting quantum fluctuations, making muon g-2 a key test of the Standard Model...
2026-08-03