Summary: arXiv:hep­ph/9809339
v1
11
Sep
1998
The Classical Approximation for Real-Time Scalar Field Theory at Finite
Temperature 
Gert Aarts
Institute for Theoretical Physics, Utrecht University
Princetonplein 5, 3508 TA Utrecht, the Netherlands
aarts@phys.uu.nl
(September 1, 1998)
The use of classical thermal eld to approximate real-time quantum thermal eld theory is
discussed. For a  4 theory, it is shown that the classical Rayleigh-Jeans divergence can be canceled
with the appropriate counterterms, and a comparison is made between the classical and quantum
perturbative expansion. It is explained why Hard Thermal Loops prevent the same method to work
for gauge theories.
I. INTRODUCTION
Real-time dynamics of quantum elds plays an im-
portant role in the early universe (baryogenesis, in a-

Source: Aarts, Gert - Department of Physics, University of Wales Swansea

Collections: Physics