HEP/Astro Seminar, Wednesday 24 September 1997

Effective Field Theory at Finite Temperature

Jens Andersen (The Ohio State University)

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Abstract

In this talk I will discuss the effective field theory approach to finite 
temperature field theory. The basic idea is that in the imaginary time 
formalism there is a summation over Matsubara frequencies in loop diagrams. 
These frequencies which are $2\pi nT$ for bosons and $(2n+1)\pi T$ for 
fermions act as (tree level) masses in the propagators. The Appelquist-
Carrazone theorem then suggests that the nonzero bosonic modes as well as 
the fermionic modes decouple at long distances. One can then construct an 
effective three-dimensional field theory which is valid at long distances 
and which can be used in calculating physical quantities. I illustrate 
these ideas and methods by calculating the screening mass in 
$g^2\Phi^4$-theory.

3:30pm, Smith Lab 4079