Conformal Field Theory for the Superstring in a Ramond-Ramond Plane Wave   Background
  A quantizable worldsheet action is constructed for the superstring in a supersymmetric plane wave background with Ramond-Ramond flux. The action is manifestly invariant under all isometries of the background and is an exact worldsheet conformal field theory. 
Nathan Berkovits (IFT/UNESP, Sao Paulo)