Search for pentaquarks decaying to Ξ π in deep inelastic scattering at HERA

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) -> 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. (c) 2005 Elsevier B.V. All rights reserved.