Warm Pions in Real Time

Abstract

The analytic continuation of correlation functions of composite operators from spacelike to timelike momenta is an open problem. In this talk we report on the analytic continuation of pion propagators using an effective field theory at finite temperature just below the finite temperature cross over of QCD. The spectral function is seen to be non-trivial. As a result, neither the screening nor the pole mass of the Euclidean propagators are equal to the mass in the Minkowski theory. Similarly, the “pion decay constant” computed in Euclidean is not the same as that in real time.