Narrow Pentaquark States in a Quark Model with Antisymmetrized Molecular Dynamics

Abstract

The exotic baryon ${\Theta }^{+}(uudd\bar{s})$ is studied with microscopic calculations in a quark model by using a method of antisymmetrized molecular dynamics(AMD). We predict narrow states, $J^{\pi }=1/2^{+}(I=0)$, $J^{\pi }=3/2^{+}(I=0)$, and $J^{\pi }=3/2^{-}(I=1)$, which nearly degenerate in a low-energy region of the $uudd\bar{s}$ system. We discuss $NK$ decay widths and estimate them to be $\Gamma <7$ for the $J^{\pi }=\{1/2^{+},3/2^{+}\}$, and $\Gamma <1$ MeV for the $J^{\pi }=3/2^{-}$ state.

Comments: Talk given at International Workshop on PENTAQUARK04, Spring-8, Hyogo, Japan, 20-23 Jul 2004