1993/07/26 by T. S. Evans, Evans, T. S.
Physics and Astronomy · #FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph) #hep-ph
paper · pdf · doi:10.48550/arxiv.hep-ph/9307335
13 pages, LaTeX (3 PS figures appended), Imperial/TP/92-93/45
arxiv created 1993/07/26 · arxiv updated 2009/11/30
The zero four-momentum and equal mass limits are taken for the bubble diagram of scalar fields. It is seen that RTF and ITF are in complete agreement. However contributions from this diagram to both retarded and time-ordered functions do depend on the order of the limits and can be infinite in some cases. This shows explicitly that the relation between the free energy and a derivative expansion of a thermal effective action is generally much more complicated that is the case at zero temperature.