ANOMALOUS GLUON CONTENT OF THE PROTON

The proton matrix element of the flavor singlet axial current is evaluated using the large Nc chiral dynamics satisfying the anomalous Ward-Takahashi identities. We relate the quark and gluon contributions (Δq and Δg) of the matrix element to the nucleon-meson (η, η′, π0) pseudo-scalar coupling constants. It is shown that the weak η′-nucleon coupling is preferred to reproduce the recent EMC data. The origin of the anomalous value of Δg pointed out by Cheng and Li is clarified in the context of the large isospin violation due to the anomaly. A subtlety related to the matrix element of the gauge-variant topological current Kμ is also discussed. © 1990.