Heavy quark solitons in the Nambu-Jona-Lasinio model.

Abstract

The Nambu-Jona-Lasinio (NJL) model is extended to incorporate heavy quark spin symmetry. In this model baryons containing one heavy quark are analyzed as bound states of light baryons, represented as chiral solitons, and mesons containing one heavy quark. From related studies in Skyrme-type models, the ground-state heavy baryon is known to arise for the heavy meson in a $P$-wave configuration. In the limit of an infinitely large quark mass the heavy meson wave function is sharply peaked at the center of the chiral soliton. Therefore, the bound state equation reduces to an eigenvalue problem for the coefficients of the operators contained in the most general $P$-wave ansatz for the heavy meson. Within the NJL model a novel feature arises from the coupling of the heavy meson to the various light quark states. In this respect conceptual differences to Skyrme-model calculations are discovered: The strongest bound state is given by a heavy meson configuration, which is completely decoupled from the grand spin zero channel of the light quarks.