REDUCTION OF STRINGY SCATTERING-AMPLITUDES THROUGH MASSIVE WARD IDENTITIES

Abstract

It is shown that the scattering amplitudes of some degenerate massive string states can be expressed in terms of that of higher spin states at the same mass level. This phenomenon is discussed from sigma-model point of view and demonstrated explicitly by using massive Ward identities generated by zero-norm states at D = 26. The subtlety of the scalar propagating state is briefly pointed out. We also compare our on-shell gauge symmetry derived from sigma-model with off-shell gauge symmetry of covariant string field theo