Abstract :
As a step toward satisfactory understanding of the quantum dynamics of Dirichlet (D-) particles, the amplitude for the basic process describing the scattering of two quantized D-particles is computed in bosonic string theory. The calculation is performed and cross-checked using three different methods, namely, (i) the path integral, (ii) the boundary state, and (iii) the openchannel operator formalism. The analysis is exact in a′ and includes the first-order correction in the expansion with respect to the acceleration of the D-particles. The resultant Lorentz-invariant amplitude is capable of describing general non-forward scattering with recoil effects fully taken into account and it reproduces the known result for the special case of forward scattering in the limit of an infinitely large D-particle mass. The expected form of the amplitude for the supersymmetric case is also briefly discussed.
