Spin-3/2 pentaquark in the QCD sum rule

Abstract

We study $IJ^P=0{3/2}^\pm$ and $1{3/2}^\pm$ pentaquark states with $S=+1$ in the QCD sum rule approach. The QCD sum rule for positive parity states and that for negative parity are independently derived. The sum rule suggests that there exist the $0{3/2}^-$ and the $1{3/2}^-$ states. These states may be observed as extremely narrow peaks since they can be much below the $S$-wave threshold and since the only allowed decay channels are $NK$ in $D$-wave, whose centrifugal barriers are so large that the widths are strongly suppressed. The $0{3/2}^-$ state may be assigned to the observed $\Theta^+(1540)$ and the $1{3/2}^-$ state can be a candidate for $\Theta^{++}$.