The Dye That Binds: Discovering the Gluon

As part of a long-range project to record the history of the Standard Model of particle physics, I am currently researching a comprehensive history of the conception, elaboration and discovery of the gluon — the gauge boson responsible for transmitting the strong force among quarks. Initially conceived by Murray Gell-Mann in 1964, this idea was substantially elaborated upon in the ensuing decade, especially after the emergence of asymptotically free field theories and quantum chromodynamics in 1973. In this lecture I will focus on the 1979 elucidation of three-jet events in the hadronic final state of electron-positron interactions at the PETRA collider at DESY, which were accepted by the high-energy physics community as conclusive evidence for the existence of a new elementary particle. Significant controversy erupted after all four PETRA collaborations revealed evidence for these events at the Lepton-Photon Symposium held that year at Fermilab. I will argue that this priority battle resulted in part due to subtle cultural differences among these groups, along the lines of what Peter Galison has dubbed the "image" and "logic" experimental traditions in microphysics. In the final analysis, it was the combination of these differing but congruent interpretations of the e⁺e^– —> hadrons data that ultimately convinced the high-energy physics community that the expected gluon had been discovered.