Abstract:
A search for a manifestly exotic S=-2 baryon state decaying to Xi-pi-, and its neutral partner decaying to Xi-pi+, has been performed using 220 pb-1 of p[overline p] collisions at sqrt(s)=1.96 TeV collected by the Collider Detector at Fermilab. The Xi- trajectories were measured in a silicon tracker before their decay, resulting in a sample with low background and excellent position resolution. No evidence was found for S=-2 pentaquark candidates in the invariant mass range of 1600--2100 MeV/c2. Upper limits on the product of pentaquark production cross section times its branching fraction to Xi-pi+,-, relative to the cross section of the well-established Xi(1530) resonance, are presented for neutral and doubly negative candidates with pT>2 GeV/c and |y|<1 as a function of pentaquark mass. At 1862 MeV/c2, these upper limits for neutral and doubly negative final states were found to be 3.2\% and 1.7\% at the 90\% confidence level, respectively.