Fermions in Black Hole Space-Time: Hawking Radiation and Back Reaction
  The leading order correction to the metric of a Schwarzschild black hole, due to the backreaction of infalling fermionic matter fields, is shown to produce a shift of the event horizon such that particles that would constitute Hawking radiation at late retarded times are now trapped. Fermionic field operators associated with infalling and outgoing modes at the horizon behave canonically in the semiclassical approximation. They are, however, shown to satisfy a nontrivial exchange algebra given in terms of the backreaction, when the shift is `quantized' by means of correspondence. The consequent exchange algebra for bilinear fermionic densities is also obtained. 
Arundhati Dasgupta, Parthasarathi Majumdar