Chiral unitary approach to the πN∗N∗ , ηN∗N∗ couplings for the N∗(1535) resonance Original Research Article

Using a chiral unitary model in which the negative parity nucleon resonance N∗≡N∗(1535) is generated dynamically by means of the Bethe–Salpeter equation with coupled meson–baryon channels in the S=0 sector, we have obtained the π0N∗N∗ and ηN∗N∗ couplings. The π0N∗N∗ coupling has smaller strength but the same sign as the π0NN coupling. This rules out the mirror assignment of chiral symmetry where the ground state nucleon N and the negative parity resonance N∗ are envisaged as chiral partners in the baryon sector.