χ-SU(3) BETHE SALPETER MODEL: EXTENSION TO SU(6) AND SU(8) SPIN-FLAVOR SYMMETRIES
Abstract
Consistent SU(6) and SU(8) spin-flavor extensions of the SU(3) flavor Weinberg-Tomozawa (WT) meson-baryon chiral Lagrangian are constructed, which incorporate vector meson degrees of freedom. In the charmless sector, the on-shell approximation to the Bethe-Salpeter (BS) approach successfully reproduces previous SU(3) WT results for the lowest-lying s–wave negative parity baryon resonances. It also provides some information on the dynamics of heavier ones and of the lightest d-wave negative parity resonances, as e.g. the Λ(1520). For charmed baryons the scheme is consistent with heavy quark symmetry, and our preliminary results in the strangeness-less charm C = +1 sector describe the main features of the three-star JP = 1/2− Λc(2595) and JP = 3/2− Λc(2625) resonances. We also find a second broad JP = 1/2− state close to the Λc(2595).
