On supersymmetric $Dp - \bar D p$ brane solutions
  We analyze in the spirit of hep-th/0110039 the possible existence of supersymmetric $D p - \bar D p$ brane systems in flat ten dimensional Minkowski space. For $p=3,4$ we show that besides the solutions related by T-duality to the $D2 - \bar D 2$ systems found by Bak and Karch there exist other ansatz whose compatibility is shown from general arguments and that preserve also eight supercharges, in particular a $D4 - \bar D4$ system with D2-branes dissolved on it and Taub-NUT charge. We carry out the explicit construction in Weyl basis of the corresponding Killing spinors and conjecture the existence of new solutions for higher dimensional branes with some compact directions analogous to the supertube recently found. 
Adri\'an R. Lugo