Transformations of real-time finite-temperature Feynman rules

Abstract

We consider transformations of the $2\times 2$ propagator matrix in real-time finite-temperature field theory, resulting in transformed $n$--point functions. As special cases of such a transformation we examine the Keldysh basis, the retarded/advanced $RA$ basis, and a Feynman-like $F\bar{F}$ basis, which differ in this context as to how ``economically'' certain constraints on the original propagator matrix elements are implemented. We also obtain the relation between some of these real-time functions and certain analytic continuations of the imaginary-time functions. Finally, we compare some aspects of these bases which arise in practical calculations.

Comments: 21 pages, LaTeX, no figures, ITFA-94-15, ENSLAPP-A-471/94, NSF-ITP-94-61