Parity of Θ+ (1540) from QCD sum rules

The QCD sum rule for the pentaquark theta(+), first analyzed by Sugiyama, Doi and Oka, is reanalyzed with a phenomenological side that explicitly includes the contribution from the two-particle reducible kaon-nucleon intermediate state. The magnitude for the overlap of the theta(+) interpolating current with the kaon-nucleon state is obtained by using soft-kaon theorem and a separate sum rule for the ground state nucleon with the pentaquark nucleon interpolating current. It is found that the K-N intermediate state constitutes only 10% of the sum rule so that the original claim that the parity of theta(+) is negative remains valid. (c) 2005 Elsevier B.V. All rights reserved.