Real-time observables from Euclidean thermal correlation functions

In this work we apply a local quantum field theory (QFT) approach in order to analyze the connection between real-time observables and Euclidean thermal correlation functions. In particular, using data generated from the functional renormalization group (FRG) in the quark-meson model, we demonstrate that in-medium effects can be directly extracted from the spatial momentum dependence of the Euclidean propagators, in contrast to conventional approaches, which rely on the reconstruction from different Matsubara frequencies. As an application, we determine the analytic features that arise from the discrete spectral contribution to the pion correlation function, and calculate the nonperturbative shear viscosity arising from these states.