TREE SCATTERING-AMPLITUDES OF THE SPIN-4 3 FRACTIONAL SUPERSTRING .2.THE TWISTED SECTORS/

The spin-4/3 fractional superstring is characterized by a world-sheet chiral algebra involving spin-4/3 currents. The discussion of the tree -level scattering amplitudes of this theory presented in the preceding paper is expanded to include amplitudes containing two twisted-sector states. These amplitudes are shown to satisfy spurious state decoupli ng. The restriction to only two external twisted-sector states is due to the absence of an appropriate dimension-one vertex describing the e mission of a single twisted-sector state. This is analogous to the ''o ld covariant' formalism of ordinary superstring amplitudes in which an appropriate dimension-one vertex for the emission of a Ramond-sector state is lacking. Examples of tree scattering amplitudes are calculate d in a c = 5 model of the spin-4/3 chiral algebra realized in terms of free bosons on the string world sheet. The target space of this model is three-dimensional flat Minkowski space-time and the twisted-sector physical states are fermions in space-time. Since the critical centra l charge of the spin-4/3 fractional superstring theory is 10, this c = 5 model is not consistent at the string loop level.