Dynamical effect on parametric x-ray radiation

There are two models which describe the origin of "parametric x-ray radiation" (PXR): the dynamical ("quasi-Cerenkov") model and the kinematical model. A theory is developed that unifies the two models. An analytic expression is obtained which gives a certain dynamical effect at high energies while reduced to the kinematical formula at low energies. A Green function analysis cleary shows that dynamical effect is not essential for the description of PXR.