High energy string–brane scattering for massive states Original Research Article

String–brane interactions provide an ideal framework to study the dynamics of the massive states of the string spectrum in a non-trivial background. We present here an analysis of tree-level amplitudes for processes in which an NS–NS string state from the leading Regge trajectory scatters from a D-brane into another state from the leading Regge trajectory, in general of a different mass, at high energies and small scattering angles. This is done by using world-sheet OPE methods and effective vertex operators. We find that this class of processes has a universal dependence on the energy of the projectile. We then compare the result for these inelastic processes with that which one would obtain from the eikonal operator in a non-trivial test of its ability to describe transitions between different string mass levels. The two are found to be in agreement.