Physics Colloquium, October 4, 2005

Homeless Mesons

Stephen L. Olsen

University of Hawaii at Manoa

There has been considerable interest in recent years in the possible existence of hadrons that do not fit into the quark-antiquark meson or three-quark baryon arrangements prescribed by the quark model. This has been mainly stimulated by numerous claimed observations of pentaquark baryons. In addition, the BaBar and Belle B-factory experiments have reported observation of mesons --the X(3872), Y(3940) & Y(4260)-- that do not fit in any obvious way expectations for conventional quark-antiquark mesons. While the existence or nonexistence of pentaquark baryons is a subject of considerable controversy, the X & Y mesons are experimentally well established. Here the main question, and the subject of my talk, is whether or not these mesons are elements of some new type of spectroscopy or evidence of deficiencies in our basic understanding of quark-antiquark systems.

Dr. Olsen's Photo

3.30 p.m.,Robert Smith Seminar Room 1080, PRB

Refreshments served at 3:00 p.m., Atrium, PRB