UConn Physics Colloquium

Discovery of the Pentaquark: An Exotic Baryon

Professor Ken Hicks

Ohio University

The pentaquark is a fundamental particle made up of 4 quarks and one antiquark, as compared with baryons (3-quarks) and mesons (quark-antiquark) which encompass virtually all known strongly-interacting particles. Although pentaquarks, along with other multi-quark particles, can exist by the rules of QCD, none had been found before last year when one called the Q+ was announced by an experimental collaboration working at the SPring-8 facility in Japan. The Q+ is composed of 2 up quarks, 2 down quarks, and 1 anti-strange quark. It was predicted in 1997 by theoretical calculations using the chiral soliton model. The SPring-8 discovery sparked a number of other experimental announcements by ITEP, CLAS and SAPHIR collaborations. This talk will describe the theoretical motivation, the subsequent announcements by SPring-8 and CLAS collaborations (the speaker is a member of both experiments), and the theoretical speculations that followed. The announcement of the pentaquark received wide media coverage, some calling it a "new classification of matter". The implications of this discovery will be discussed briefly.

Friday, August 29, 2003
3:30 PM
Biology/Physics Building
Room BSP130

(Refreshments will be served immediately following the colloquium in the lobby outside the lecture hall)

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