Dispersive estimates for Schroedinger operators in the presence of a   resonance and/or an eigenvalue at zero energy in dimension three: II
  We consider non-selfadjoint operators of the kind arising in linearized NLS and prove dispersive bounds for the time-evolution without assuming that the edges of the essential spectrum are regular. Our approach does not depend on any specific properties of NLS. Rather, it is axiomatic on the linear level, and our results are obtained from four assumptions (which are of course motivated by NLS). This work is in three dimensions. 
Mehmet Burak Erdogan, Wilhelm Schlag