Orbits of a String around a Fivebrane
  The classical orbits of a test string in the transverse space of a singular heterotic fivebrane source are classified. The orbits are found to be either circular or open, but not conic because the inverse square law is not satisfied at long range. This result differs from predictions of General Relativity. The conserved total angular momentum contains an intrinsic component from the fivebrane source, analogous to the electron-monopole case. 
Ramzi R. Khuri and HoSeong La