Excited Baryon Production and Decays

Abstract

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.

Comments: 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 pages