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Limits for the central production of Theta+ and Xi-- pentaquarks in 920 GeV pA collisions

B Collaboration, I. Abt

hep-exarXiv:hep-ex/0408048

Abstract

We have searched for Theta+(1540) and Xi--(1862) pentaquark candidates in proton-induced reactions on C, Ti and W targets at mid-rapidity and s = 41.6 GeV. In 2x108 inelastic events we find no evidence for narrow (sigma~5 MeV) signals in the Theta+ -> pKs and Xi-- -> Xi-pi- channels; our 95% CL upper limits (UL) for the inclusive production cross section times branching fraction Bx(dsigma/dy)|y~0 are 3.7 and 2.5 microb/N. The UL of the yield ratio of [Theta+ / Lambda(1520)] < 2.7% is significantly lower than model predictions. Our UL of [BxXi-- / Xi(1530)0] < 4% is at variance with the results that have provided first evidence for the Xi-- signal.

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