Search for exotic S=-2 baryons in pp̄ collisions at s=1.96TeV

A search for a manifestly exotic S=-2 baryon state decaying to Ξ-π-, and its neutral partner decaying to Ξ-π+, has been performed using 220pb-1 of pp collisions at s=1.96TeV collected by the Collider Detector at Fermilab. The Ξ- 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 1600-2100MeV/c2. Upper limits on the product of pentaquark production cross section times its branching fraction to Ξ-π+,-, relative to the cross section of the well-established Ξ(1530) resonance, are presented for neutral and doubly negative candidates with pT>2GeV/c and