Radiative corrections with 5D mixed position-/momentum-space propagators

In higher dimensional field theories with compactified dimensions there are three standard ways to do perturbative calculations: (i) by the summation over Kaluza-Klein towers; (ii) by the summation over winding numbers making use of the Poisson-resummation formula; and (iii) by using mixed propagators, where the coordinates of the four infinite dimensions are Fourier-transformed to momentum space while those of the compactified dimension are kept in configuration space. The third method is broadly used in finite temperature field theory calculations. One of its advantages is that one can easily separate the ultraviolet divergent terms of the uncompactified theory from the non-local finite corrections arising from windings around the compact dimensions. In this note we demonstrate the use of this formalism by calculating one-loop self-energy corrections in a 5D theory formulated on the manifold and on the orbifold .