Nucleon Axial Couplings and [(1/2,0)Circle Plus(0,1/2)]-[(1,1/2)Circle Plus(1/2,1)] Chiral Multiplet Mixing

Abstract

Three-quark nucleon interpolating fields in QCD have well-defined SU(L)(2) x SU(R)(2) and U(A)(1) chiral transformation properties. Mixing of the [(1/2, 0) circle plus (0, 1/2)] chiral multiplet with one of four available [(1/2, 0) circle plus (0, 1/2)] or [(0, 1/2) circle plus (1/2, 0)] representations can be used to fit the isovector axial coupling g(A)((1)) A and thus predict the isoscalar axial coupling g(A)(0) of the nucleon, in reasonable agreement with experiment. We also use a chiral meson-baryon interaction to calculate the masses and one-pion-interaction terms of J=1/2 baryons belonging to the [(0, 1/2) circle plus (1/2, 0)] and [(1, 1/2) circle plus (1/2, 1)] chiral multiplets and fit two of the diagonalized masses to the lowest-lying nucleon resonances thus predicting the third J=1/2 resonance at 2030 MeV, not far from the (one-star PDG) state Delta(2150)