Pentaquarks: Theory overview, and some more about quark models

After reviewing the basics, topics in this talk include an attempted survey of theoretical contributions to this workshop, some extra specific comments on quark models, and a summary.Comment: Invited talk at Pentaquark04, hosted by SPring-8, Harima Science Garden City, Japan, July 200

Excited Baryon Production and Decays

We consider decays of the lowest-lying positive parity 56-plet and negative parity bf 70-plet excited baryons. For the 70-plet, we include both single-quark and two-quark decay operators, and find, somewhat mysteriously, that the two-quark operators are not phenomenologically important. Studies of decays 70-plet to Delta(1232) + photon may strengthen or vitiate this observation. For the 56-plet decays, now using only the single-quark operator, we can predict many strong decays after fitting parameters on the assumption that the Roper is a 3q state. Comparison of these predictions to experiment can verify the structure of the 56-plet. As a sidelight, we show a large N_c derivation of the old Gursey-Radicati mass formula.Comment: Invited talk at the workshop on The Phenomenology of Large Nc QCD, held at Arizona State University, Tempe, AZ, USA, 9-11 January 2002, 9 page