NUCLEON AXIAL COUPLINGS AND [(½,0) ⊕ (0,½)]-[(1,½) ⊕ (½,1)] CHIRAL MULTIPLET MIXING

Abstract

Three-quark nucleon interpolating fields in QCD have well-defined SU L(2) × SU R(2) and U A(1) chiral transformation properties. Mixing of the [(1,½) ⊕ (½,1)] chiral multiplet with one of four available [(½,0) ⊕ (0,½)] or [(0,½) ⊕ (½,0)] representations can be used to fit the isovector axial coupling [Formula: see text] and thus predict the isoscalar axial coupling [Formula: see text] 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 = ½ baryons belonging to the [(0,½) ⊕ (½,0)] and [(1,½) ⊕ (½,1)] chiral multiplets and fit two of the diagonalized masses to the lowest-lying nucleon resonances thus predicting the third J = ½ resonance at 2030 MeV, not far from the (one-star PDG) state Δ(2150).