NN,N\Delta Couplings and the Quark Model
  We examine mass-corrected SU(6) symmetry predictions in the quark model relating vector, axial-vector and strong NN and N\Delta couplings, and demonstrate that the experimental N\Delta value is significantly higher than predicted in each case. Nevertheless the Goldberger-Treiman relation is satisfied in both sectors. Possible origins of the discrepancy of the quark model predictions with experiment are discussed. 
Thomas R. Hemmert, Barry R. Holstein and Nimai C. Mukhopadhyay