Heavy Quark Symmetry and the Skyrme Model

Abstract

We present a consistent way of describing heavy baryons containing a heavy quark as bound states of an $SU(2)$ soliton and heavy mesons. The resulting mass formula reveals the heavy quark symmetry explicitly. By extending the model to the orbitally excited states, we establish the generic structure of the heavy baryon spectrum. As anticipated from the heavy quark spin symmetry, the $c$-factor denoting the hyperfine splitting constant {\em vanishes} and the baryons with the same angular momentum of light degrees of freedom form degenerate doublets. This approach is also applied to the pentaquark exotic baryons, where the conventional $c$-factor plays no more a role of the hyperfine constant. After diagonalizing the Hamiltonian of order $N_c^{-1}$, we get the degenerate doublets, which implies the vanishing of genuine hyperfine splitting.