Topological expansion for baryons and mesons

Abstract

A method of including baryons in the topological classification scheme of Veneziano is described. Every amplitude is classified in terms of the number of handles and boundaries of an associated surface. This classification is purely topological. It does not refer to numbers of flavorsN, or rely on an equalityN −1∼-g 2 that is supposed to be a consequence of the topological expansion. The lowest-order amplitudes are associated with surfaces that have a characteristic tree structure. The analog of Veneziano’s planar-discontinuity formula holds.