Bound States of Branes with Minimal Energy
  It is pointed out that the energy of the bound states of D-branes and strings is determined by the central charge of the space-time supersymmetry. The universality which is seen at the black hole horizon appears also on the D-brane side: the total energy of the bound states of a given number of branes has a minimum when considered as a function of the independent parameters (moduli). This provides a new evidence that the near-horizon space-time geometry of the dilaton black holes can be represented by the bound states of branes. The axion-dilaton dyonic black holes have the mass formula of the non-threshold type bound state. Upon uplifting to higher dimensions they may give information about such states. 
Renata Kallosh