Superconformal mechanics, black holes, and non-linear realizations
  The OSp(2|2)-invariant planar dynamics of a D=4 superparticle near the horizon of a large mass extreme black hole is described by an N=2 superconformal mechanics, with the SO(2) charge being the superparticle's angular momentum. The {\it non-manifest} superconformal invariance of the superpotential term is shown to lead to a shift in the SO(2) charge by the value of its coefficient, which we identify as the orbital angular momentum. The full SU(1,1|2)-invariant dynamics is found from an extension to N=4 superconformal mechanics. 
J. A. de Azcarraga, J. M. Izquierdo, J. C. Perez Bueno and P. K.   Townsend