Prediction of Narrow $J^π=1/2^+$, $3/2^+$, and $3/2^-$ states of $Θ_+$ 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. We predict that the lowest even state is $J^π=1/2^+(I=0)$ or $J^π=3/2^+(I=0)$, and the lowest odd state is $J^π=3/2^-(I=1)$. They nearly degenerate in the $uudd\bar{s}$ system. We discuss $K^+n$ 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.