Real Time Correlation Functions at Finite Temperature and their Classical Limit
In order to investigate the reliability of the classical approximation for non-perturbative real time correlation functions at finite temperature we study the two-point correlator for the anharmonic oscillator. For moderately large times the classical limit gives a good approximation of the quantum result but after some time $t_*$ the classical approximation breaks down even at high temperature.
hep-ph↗