Unitarity Constraint upon Kinematical Analyses of the GSI Time-Modulated   Radioactive Decay Experiment
  It is tempting to try to explain the reported time-modulated decay rate in the GSI experiment by arguing that the matrix element for decay at any time results in an interference between two slightly different momentum values in the parent ion beam. I show here that a unitarity theorem of quantum mechanics rules out a wide class of such explanations. 
Murray Peshkin