Pentaquark decay is suppressed by chirality conservation

It is shown that, if the pentaquark (Theta ^ + = uuddbar s) baryon can be represented by the local quark current η_Θ, its decay Θ⁺→nK⁺(pK⁰) is forbidden in the limit of chirality conservation. The Θ⁺ decay width Γ is proportional to (alpha _s^2 leftlangle {0left| {bar qq} right|0} rightrangle ^2), where (leftlangle {0left| {bar qq} right|0} rightrangle ,q = u,d,s), is quark condensate, and, therefore, is strongly suppressed. The polarization operator of the pentaquark current is calculated using the operator product expansion. The Θ⁺ mass found by the QCD sum rules method is in reasonable agreement with experiment.