  The QCD sum rule technique is employed to investigate pentaquark states with
strangeness S = +1 and IJ^P = 0,1/2^\pm, 1,1/2^\pm, 0,3/2^\pm, 1,3/2^\pm.
Throughout the calculation, emphasis is laid on the establishment of a valid
Borel window, which corresponds to a region of the Borel mass, where the
operator product expansion converges and the presumed ground state pole
dominates the sum rules. Such a Borel window is achieved by constructing the
sum rules from the difference of two independent correlators and by calculating
the operator product expansion up to dimension 14. Furthermore, we discuss the
possibility of the contamination of the sum rules by possible KN scattering
states. As a result, we conclude that the 0,3/2^+ state seems to be the most
probable candidate for the experimentally observed \Theta^+(1540), while we
also obtain states with 0,1/2^-, 1,1/2^-, 1,3/2^+ at somewhat higher mass
regions.
