Spectral functions from the real-time functional renormalization group
S. Huelsmann (Fakultät für Physik, Universität Bielefeld, D-33615 Bielefeld, Germany); S. Schlichting (Fakultät für Physik, Universität Bielefeld, D-33615 Bielefeld, Germany); P. Scior (Fakultät für Physik, Universität Bielefeld, D-33615 Bielefeld, Germany)
We employ the functional renormalization group approach formulated on the Schwinger-Keldysh contour to calculate real-time correlation functions in scalar field theories. We provide a detailed description of the formalism, discuss suitable truncation schemes for real-time calculations, as well as the numerical procedure to self-consistently solve the flow equations for the spectral function. Subsequently, we discuss the relations to other perturbative and nonperturbative approaches to calculate spectral functions and present a detailed comparison and benchmark in dimensions.
