Physicists working with data from the STAR detector at RHIC have found evidence suggesting that baryon number may not be carried solely by the three valence quarks inside a proton. Instead, the results point to a Y-shaped structure of gluons, known as a *baryon junction*, that connects the proton’s quarks and may play a key role in transporting baryon number. The finding challenges the simplified textbook picture of the proton and could provide new insights into one of the fundamental questions of physics: why matter remains stable and why the universe contains far more matter than antimatter. The researchers’ analysis found an excess of baryons that could not be fully explained by the number of quarks stopped during the collisions, suggesting that the gluon junction may provide part of the missing explanation.
