More on mixed boundary conditions and D-branes bound states

In this article, applying different types of boundary conditions; Dirichlet, Neumann, or Mixed, on open strings we realize various new brane bound states in string theory. Calculating their interactions with other D-branes, we find their charge densities and their tension. A novel feature of (p - 2,p) brane bound state is its "non-commutative" nature which is manifestly seen both in the open strings mode expansions and in their scattering off a D-p-brane. Moreover we study three or more object bound states in string theory language. Finally we give a M-theoretic picture of these bound states. (C) 1998 Elsevier Science B.V. All rights reserved.