Is there a Vector Boson Coupling to Baryon Number?

Discrepancies in measurements of the QCD running coupling constant are consistent with a new vector gauge boson coupling to baryon number with strength aB~0.1. Upsilon decays constrain such a boson to have a mass greater than about 35 GeV. It is difficult to observe such a boson in Z decays, e+e- annihilation, or hadronic interactions.