Do Chiral Soliton Models Predict Pentaquarks?

Abstract

We reconsider the relationship between the bound state and the SU(3) rigid rotator approaches to strangeness in chiral soliton models. For non-exotic $S=-1$ baryons the bound state approach matches for small $m_K$ onto the rigid rotator approach, and the bound state mode turns into the rotator zero-mode. However, for small $m_K$, there are no $S=+1$ kaon bound states or resonances in the spectrum. This shows that for large $N$ and small $m_K$ the exotic state is an artifact of the rigid rotator approach. An $S=+1$ near-threshold state with the quantum numbers of the $Θ^+$ pentaquark comes into existence only when sufficiently strong SU(3) breaking is introduced into the chiral lagrangian. Therefore, pentaquarks are not generic predictions of the chiral soliton models.

Contribution to proceedings of QCD 2004