Search for exotic S =-2 baryons in p(p)over-bar collisions at root s=1.96 TeV

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 pp collisions at root 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/c(2). 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 p(T) > 2 GeV/c and vertical bar y vertical bar < 1 as a function of pentaquark mass. At 1862 MeV/c(2), 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.