WORLD-SHEET DYNAMICS OF STRING JUNCTIONS

We analyze scattering of string modes at string junctions of type IIB string theory. In the infrared limit, certain orthogonal linear combin ations of the fields on the different strings satisfy either Dirichlet or Neumann boundary conditions. We confirm that the world-sheet theor y of a general string network has eight conserved supercharges in agre ement with target space BPS considerations. As an application, we obta in the band spectrum of some simple string lattices. (C) 1998 Elsevier Science B.V.