Theta++ from QCD sum rule

Abstract

We study the pentaquark $uudd\bar{s}$ with $J=3/2$ and I=1 (${\Theta }^{++}$) in the QCD sum rule approach. We derive the QCD sum rules for positive and negative parity states of the pentaquark. The QCD sum rule predicts that there exists ${\Theta }^{++}$ with negative parity and its mass is $1.5\sim 1.6$ GeV. The negative parity ${\Theta }^{++}$ can be extremely narrow, since it lies much below the $\Delta K$ threshold and the decay into $KN$ state is strongly suppressed due to the $D$-wave centrifugal barrier. Also, the possibility of the existence of the ${\Theta }^{++}$ with positive parity is not excluded. Although it nearly degenerates with the negative parity state, it may be broader than the negative parity state.

5 pages, 4 figures