Quark spin coupling in baryons reexamined

A direct connection can be made between mixing angles in negative parity baryons and the spin coupling of constituent quarks. The mixing angles do not depend on spectral data. These angles are recalculated for gluon exchange and pion exchange between quarks. The mixing determined for pion exchange is in disagreement with a calculation in the literature [Phys. Rep. 268, 263 (1996)], but consistent with the results of another calculation [Phys. Rev. C 65, 045209 (2002)] and with experiment. The experimental data on mixing are very similar to those derived from gluon exchange but substantially different from the values obtained for pion exchange. A preliminary estimate of spin orbit forces is found to give only small changes in these angles