Dual-model spectrum analysis, using Virasoro-algebra representations

Abstract

The spectrum of states in the unit intercept Veneziano model is studied by noticing that there is exactly one physical state in each irreducible representation of the Virasoro algebra for spacelike momenta. The squared norms of the continued physical states are fully enumerated. A method of analytic continuation from the spacelike to the timelike domain is described. As an illustrative example of its usefulness, the lower limit of Del Guidice, Di Vecchia and Fubini for the number of positive squared norm physical states on mass shell is rederived; the states obtained in this way are of definite spin.