THE SINGLET AXIAL-VECTOR COUPLING IN THE EFFECTIVE MESON BARYON LAGRANGIAN

The Goldberger-Treiman (GT) relation in the singlet channel, being con sistent with the EMC experimental results, can be manifested in an ext ended sigma model in which the chiral symmetry in the singlet channel is realized in the parity doublet model by assuming that the excited n ucleon state S-11 N(1535) is the parity partner of the nucleon state. The model gives a natural explanation of the smallness of the singlet axial vector coupling g(A)(o) without the necessity to assume a large strange sea contribution, and is unique in explaining the decay rate o f N(1535) --> N eta as well.