Structure and production of Theta+

Abstract

We study properties of the pentaquark particle Theta+ with emphasis on the role of chiral symmetry. It is shown that when chiral force is sufficiently strong, the positive parity Theta+ may be realized with a lower mass relative to the negative parity state. The decay width is then studied in the non-relativistic quark model. It is shown that the narrow width may be realized for the positive parity state, while the seemingly lowest negative parity state couples strongly to the continuum state resulting in a very broad width. Finally, Theta+ production is studied in photo-induced and proton-induced processes. The polarized proton reaction provides a model independent method to determine the parity of Theta+.