Physicists have long been puzzled by the question of how protons carry their baryon number, a quantum property that distinguishes them as matter rather than antimatter. A recent study by researchers from the STAR Collaboration at the Relativistic Heavy Ion Collider suggests that the baryon number is not only carried by the proton’s three quarks, but also by the network of gluons that bind these quarks together. This concept is known as the Baryon Junction.
Quarks and gluons in protons. Image credit: Brookhaven National Laboratory.
The traditional view of a proton as simply three quarks contributing to its properties has been challenged by more precise experiments revealing a complex system where defining properties emerge from interactions between quarks and the gluons binding them.
One of the remaining mysteries is how protons actually carry their baryon numbers, with STAR physicists noting the conservation of these quantum numbers since the formation of baryons in the early universe.
Experiments at the Relativistic Heavy Ion Collider involving particle collisions have shown that the baryon number behaves differently than expected if carried by quarks alone, suggesting a stronger support for the gluon-coupled model over the traditional quark-centered model.
Researcher Professor Zhangbu Xu of Kent State University’s Brookhaven Laboratory emphasized that their findings indicate the baryon number is more effectively carried by gluons in a specific configuration rather than by individual quarks.
This new understanding challenges the traditional view and deepens insights into the fundamental elements of the universe’s structure. The team’s paper has been published in the journal Science.
_____
STAR Collaboration. 2026. Tracking baryon numbers in nuclear collisions. Science 393 (6812): 727-731; doi: 10.1126/science.ads5962
Source: www.sci.news
