Radiative Polarization of a Rotating Charge and Construction of Green's Functions

In this dissertation several problems of Theoretical Physics are discussed, from the point of view of Source Theory. At the beginning the basic ideas of Source Theory will be introduced. Then the Green's function for a spin 0 particle will be written in hyperbolic coordinates and by comparing with the thermal Green's function, it will be evident that it is as if the comoving observer is immersed in a thermal bath of temperature: kT = hbar a/2pic. The next topic is the proof that when transforming to hyperbolic coordinates, only 3 independent polarizations for the massive spin 1 appear. This will be done explicitly for two dimensions, where only 1 polarization should appear. The major part of this dissertation is about the calculation of the radiative polarization of a rotating charge using the comoving observer point of view. The calculation will be performed both in the non-relativistic and extreme relativistic regimes, and the photonic Green's function will be constructed in the comoving system of reference. Finally a semi-classical derivation of the spin 0 Green's function in a Robertson-Walker spacetime will be given.