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 Nuclear Tuesday, October 30, 2007 3:30 PM Physics Building, Room 204 Wouter Deconinck [Host: Kent Paschke] University of Michigan "Pentaquarks: much ado about nothing?"   Slideshow (PDF) ABSTRACT:In 2003 new experimental evidence was presented for the observation of the exotic baryon Θ + (1540) with a minimal quark content $uuddar{s}$. Quickly more than ten nuclear and high energy physics experiments reported positive results, apparently confirming the existence of the Θ + (1540), but all suffered from low statistical precision. An increasing number of null results started to appear, seemingly in contradiction with the positive sightings. Now the null results dominate the positive results, often with impressive statistical precision, and cast doubt on the existence of the Θ + (1540). The experimental status will be discussed, including some recent positive results. The past contributions and ongoing efforts of the Hermes experiment will be highlighted. SLIDESHOW: