Neutrino flavor oscillations in a curved space-time
  Using a WKB approximation of the Dirac equation in a curved spacetime, we
obtain the expression for the phase shift between two neutrino mass eigenstates
in a generic gravitational field. We apply this expression to two specific
space-time geometries, namely the Kerr-Newman metric describing a rotating and
charged black hole, and the Friedmann-Robertson-Walker metric.
