Narrow Pentaquark States in a Quark Model with Antisymmetrized Molecular Dynamics

Abstract

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