Search for pentaquarks decaying to Xi-pi in deep inelastic scattering at HERA

Abstract

A search for pentaquarks decaying to Xi^{-} pi^{-} (Xi^{-} pi^{+}) and corresponding antiparticles has been performed with the ZEUS detector at HERA. The data sample consists of deep inelastic ep scattering events at centre-of-mass energies of 300 and 318 GeV, and corresponds to 121 pb^{-1} of integrated luminosity. A clear signal for Xi^{0}(1530) to Xi^{-} pi^{+} was observed. However, no signal for any new baryonic state was observed at higher masses in either the Xi^{-} pi^{-} or Xi^{-} pi^{+} channels. The searches in the antiparticle channels were also negative. Upper limits on the ratio of a possible Xi^{--}_{3/2} (Xi^{0}_{3/2}) signal to the Xi^{0}(1530) signal were set in the mass range 1650-2350 MeV.