Hidden Gluon Structure in Protons Unveiled by STAR Detector

Recent research conducted using the STAR detector at the Relativistic Heavy Ion Collider (RHIC) has unveiled a potentially paradigm-shifting understanding of proton structure. The study, published in Science, indicates that gluons, particles that bind quarks together, might play a crucial role in carrying baryon number, a fundamental quantum property of protons.

Traditionally, it was believed that the three main 'valence' quarks within a proton each carried one-third of the baryon number. However, the new findings suggest that a Y-shaped 'junction' of gluons could be responsible for this property instead. This challenges the long-standing assumption that baryon number is solely associated with quarks.

The research, led by Zhangbu Xu from Kent State University and Brookhaven Lab, utilized high-energy particle collisions at RHIC to gather evidence supporting this theory. The results showed an unexpected excess of baryons emerging perpendicular to the collision beams, suggesting that gluons might be transporting baryon number in a unique configuration.

Understanding what carries baryon number is significant beyond just the internal structure of protons. It relates to the conservation of baryon number in the universe, a principle that helps explain the stability of matter and why there is more matter than antimatter in the universe.

The STAR collaboration's findings could lead to a revision of the simplified models of protons found in textbooks, which typically describe the baryon number as being evenly distributed among the three valence quarks.