Decay for the wave and Schroedinger evolutions on manifolds with conical   ends, Part II
  Global in time dispersive estimates for the Schroedinger and wave evolutions are obtained on manifolds with conical ends whose Hamiltonian flow exhibits trapping. This paper deals with the case of initial data with fixed "nonzero angular momentum". 
Wilhelm Schlag, Avy Soffer, Wolfgang Staubach