T-DUALITY AND THE WORLDVOLUME SOLITONS OF 5-BRANES AND KK-MONOPOLES

We show that the fluxes of the various six-dimensional ''gauge'' theor ies are associated to below threshold bound states of D-branes with th e NS-5-branes and KK-monopoles which preserve half of bulk supersymmet ry. We then present the supergravity solutions that correspond to thes e bound states. In addition using the worldvolume solitons of IIA and IIB NS-5-branes and KK-monopoles, we investigate the sectors of the '' gauge'' theories that preserve one quarter of hulk supersymmetry. This leads to a generalization a supergravity solution which has the inter pretation of two intersecting NS-5-branes at a 3-brane and to the cons truction of some of the worldvolume solitons of IIA and M-theory KK-mo nopoles. Furthermore, using the IIA/IIB T-duality of the bulk theories , we give the T-duality transformations of the worldvolume solitons of NS-5-branes and KK-monopoles. We find that the worldvolume 0-brane, s elf-dual string and 2-brane solitons of NS-5-branes appear in the same T-duality chain. (C) 1998 Elsevier Science B.V. All rights reserved.