Pentaquark decay in QCD sum rules

In a diquark-diquark-antiquark picture of the pentaquark we study the decay Θ→K+n within the framework of QCD sum rules. After evaluation of the relevant three-point function, we extract the coupling gΘnK which is directly related to the pentaquark width. Restricting the decay diagrams to those with color exchange between the meson-like and baryon-like clusters reduces the coupling constant by a factor of four. Whereas a small decay width might be possible for a positive parity pentaquark, it seems difficult to explain the measured width for a pentaquark with negative parity.