Theoretical Overview of the Pentaquark Baryons

Abstract

A review is given of the theoretical ideas concerning the mysterious pentaquark baryons proposed during the first year after its discovery. We focus on the difficulties involved with the constituent quark models and the discrepancy between the QCD predictions and most of the phenomenological models.

Comments: Review based on the talk given at the YITP Workshop on ``Multi-quark Hadrons; Four, Five and More?'', held on Feb. 17-19, 2004. To be published in Progress of Theoretical Physics as an invited paper