S=+1 pentaquarks in QCD sum rules

We study pentaquark states with strangeness S=+1 and within the QCD sum rule technique. In order to obtain reliable results with this method, it is indispensable to establish a valid Borel window, where the operator product expansion (OPE) converges and the presumed ground state pole dominates the sum rules. By constructing the sum rules from the difference of two carefully chosen independent correlators and calculating the OPE up to dimension 14, such a Borel window can be established. This then leads to our main conclusion that the state with qantum numbers appears to be the most probable candidate for the experimentally observed Θ+(1540). Furthermore, states with are also obtained at slightly higher mass regions.