D-BRANE BOUNDARY STATE DYNAMICS

We construct the open string boundary states corresponding to various time-dependent deformations of the D-brane and explore several ways in which they may be used to study stringy soliton collective coordinate quantum dynamics. Among other things, we find that D-strings have exa ct moduli corresponding to arbitrary chiral excitations of the basic s oliton. These are presumably the duals of the BPS-saturated excitation s of the fundamental type IIB string. These first steps in a systemati c study of the dynamics and interactions of Dirichlet-brane solitons g ive further evidence of the consistency of Polchinski's new approach t o string soliton physics.