Electron propagator physical interpretation

If there is no explicit external electromagnetic field, the covariant field equations determine a self-interaction energy that can be interpreted as a dynamical electron mass Sm. Since this turns out to be infinite, renormalization is necessary in order to have a viable physical theory. Field quantization is required for quantitative QED. The classical field equation for the electromagnetic field can be solved explicitly using the Green function or Feynman propagator GPV, whose Fourier transform is —gllv/K2, where k = kp — kq is the 4-momentum transfer. The product of y0 and the field-dependent term in the Dirac Hamiltonian, Eq. (10.3), is... 

We have chosen to restrict our stucfy to propagation by modelling of a aystal like nitromethane This choice of this compound was determined hy interest in the diversity of behaviOTs as regards detonations (e.g. in die liquid vs. solid phases sensitivity modified by some traces of additives), and the richness of eiqierimentk other physical and chemical data as well as tiie simplicity of the chemical formula which allow both, the interpretation of experiment and the accuracy of the calculations of the electronic structure in the differ t electronic states... A body of conditions wdiich gives a heuristic character to this compound and, consequmitiy, an opening to new ideas. 

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