The Gluon Anomaly in the Proton Spin
In this lecture, we will review an important experiment on polarized muon-proton scattering carried out by the European Muon Collaboration (EMC)1) and some theoretical developments that resulted from it.2) The EMC measurement of the spin structure of deep inelastic muon scattering from protons was interpreted as indicating that essentially none of the proton’s spin was carried by the spins of its quarks. A reexamination of this interpretation held that the apparent vanishing of the quark spin contribution could be due to a cancellation between an intrinsic quark contribution and a gluonic contribution induced by the triangle diagram that gives rise to the Adler-BellJackiw anomaly.
KeywordsGauge Transformation Quark Propagator Triangle Diagram Polarization Asymmetry Quark Spin
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