Permutation group SN and large Nc excited baryons

Abstract

We study the excited baryon states for an arbitrary number of colors Nc from the perspective of the permutation group SN of N objects. Classifying the transformation properties of states and quark-quark interaction operators under SN allows a general analysis of the spin-flavor structure of the mass operator of these states, in terms of a few unknown constants parametrizing the unknown spatial structure. We explain how to perform the matching calculation of a general two-body quark-quark interaction onto the operators of the 1/Nc expansion. The inclusion of core and excited quark operators is shown to be necessary. Considering the case of the negative parity L=1 states transforming in the MS of SN, we discuss the matching of the one-gluon and the Goldstone-boson exchange interactions. © 2008 The American Physical Society.