STAR Data at RHIC Indicate Gluon Junction Carries Baryon Number in Protons

The STAR collaboration analyzed multiple collision systems at RHIC, including proton-proton and heavy-ion runs through 2025, to isolate baryon-number transport mechanisms. By comparing net-baryon yields at forward and mid-rapidity across isobaric and isospin-asymmetric systems, the team tested whether transport follows quark or gluon-junction trajectories. Results favor the junction model first outlined by Kharzeev in 1996.

This finding directly challenges the naive three-quark model used in most textbooks, where each valence quark is assigned one-third baryon number. If the junction carries the quantum number, standard parton-distribution functions and fragmentation functions require revision, altering predictions for baryon stopping in heavy-ion collisions and for the matter-antimatter asymmetry generated after the Big Bang.

Proton lifetime stability and the observed excess of matter over antimatter both hinge on precise baryon-number conservation; a gluon-based mechanism supplies a new dynamical pathway that could reconcile these observations with QCD. Confirmation would also reshape lattice-QCD calculations of proton structure and motivate new observables at the Electron-Ion Collider.

Next steps include re-analysis of existing LHCb and ALICE datasets for junction signatures plus dedicated high-luminosity RHIC runs proposed for 2027-2028 to reach 5-sigma statistical significance.