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 anti-p collisions at s**(1/2) = 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 Si- 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 |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.
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Updated: Tuesday, 2007 March 06 09:32:10 CST automatically from input from Carol Picciolo