Pentaquark search at HERMES

An experimental search for possible Θ+ and Θ++ resonances was performed using the decay modes pKS and pK+. We report evidence for a Θ+ with a statistical significance of 4σ. The absence of a peak in the pK+ spectrum in the vicinity of the Θ+ mass yields an estimate of the upper limit for the production cross section of the Θ++.