Superstring Regge amplitudes and graviton radiation at planckian energies

We introduce in (super) string theory new emission vertices for external (leading) Regge trajectories and we use them to calculate tree amplitudes with off-shell reggeized gluons and gravitons. Such Regge-Gribov vertices arise as quasi-local operators in the short-distance product of primary fields and generate coherent reggeon states. We present detailed calculations in the three- and four-reggeon cases for both the bosonic string and the superstring in the Neveu-Schwarz formalism. In particular, we derive the graviton emission current associated with high-energy scattering, which also incorporates internal line insertions. The corresponding squared current shows the absence of Coulomb singularities associated with gravitational radiation. (orig.)