Search for exotic baryons at HERMES

An experimental search for the Θ(1540)- and Λ(1520)-resonance was performed in quasi-real photoproduction on deuterium at the HERMES experiment. While evidence for Θ(1540) was found in the decay channel pK 0 S→pπ + π -, no evidence for the corresponding anti-particle was found. In some models it is expected that the Θ(1540) and the Λ(1520) have similar production mechanisms. The photoproduction cross-sections for the Λ(1520) in the decay channel Λ(1520)→pK - and the corresponding anti-particle are determined. The partial photoproduction cross-sections for Λ(1520) and ¯(1520) are obtained as σ Λ(1520) = 65.3±8.8(stat)±6.9(syst)nb and σ ¯(1520) = 9.8±2.6(stat)±0.9(syst)nb, corresponding to a ratio R Λ(1520) = σ ¯(1520)/σ Λ(1520) = 0.15±0.05(stat)±0.02(syst)