Representation Mixing and Exotic Baryons in the Skyrme Model

We study the effect of representation mixing in the SU(3) Skyme model by diagonalizing exactly the representation-dependent part. It is observed that even without the next-to-leading order symmetry breaking terms the low-lying baryon masses as well as the recently discovered $\Theta+$ and $\Cascade_{\bar{10}}$ can be fairly well reproduced within 3% accuracy. It is also demonstrated that the mixing effect is not negligible in decay processes of $\{\bar{10}\}$. In particular the effect of mixing with $\{27\}$ is found to be quite large. These results are compatible with the second-order perturbation scheme. The decay widths are found to be sensitive to the mass values. The decay widths of $\{\bar{10}\}$ are estimated to be smaller than those of $\{10\}$ by an order of magnitude due to the destuctive interference between operators although the kinematic factors are comparable.