Kobayashi-Kondo-Maskawa-t Hooft interaction in pentaquarks

Abstract

We review critically the predictions of pentaquarks in the quark model, in particular, those based on the flavor-spin-dependent (Glozman-Riska) hyperfine interaction and the color-spin (one-gluon-exchange Fermi-Breit) one. We include the antiquark interactions and find that: (1) the exotic SU(3) multiplets are not substantialy affected in the flavor-spin model, whereas some of the nonexotic multiplets are; and (2) the variational upper bound on the Xi(--)-Theta(+) mass difference in the color-spin hyperfine interaction model is substantially reduced. This leads us to the U-A(1) symmetry breaking Kobayashi-Kondo-Maskawa-tHooft interaction. We discuss some of its phenomenological consequences for pentaquarks.