Recent Results on Pentaquark Searches from STAR
Huan Zhong Huang
For the STAR Collaboration

We have observed a peak structure in p+K+ and pbar+K- invariant mass
distribution with approximately 4-5 sigma statistical significance from both
d+Au collisions at 200 GeV and Au+Au collisions at 62.4 GeV. The mass of the
observed peak is at 1530 MeV/c2 and the width is dominated by the detector
resolution. Such a structure, if confirmed as a particle, would be
manifestly exotic with uuud-sbar quark structure. The production yield is
estimated to be very small. No signal above combinatorial background was
observed in STAR p+p and Au+Au collisions at 200 GeV which are smaller data
samples. Possible formation mechanism through coalescence and its
implications on various experimental searches in nuclear and photo-
productions will be presented. We discuss perspectives for future
confirmations of our observations. The formation of dense partonic matter
and its rapid hadronization provide a unique environment for possible exotic
particle production at RHIC.