%0 Generic
%A Veschgini, Kambis
%D 2017
%F heidok:22476
%R 10.11588/heidok.00022476
%T A Combined Functional Renormalization and Mean-Field Study of Competing Orders in the Two-Dimensional Hubbard Model
%U https://archiv.ub.uni-heidelberg.de/volltextserver/22476/
%X The primary subject of this thesis is the two-dimensional Hubbard model. Using the functional renormalization Group in static approximation we will present the phase diagram of the 2D-Hubbard model and refine it by including frequency dependencies and full self-energy effects. The focus will fall on the vicinity of the quantum critical point, where the system shows a non-Fermi-liquid-like behavior. In mean-field calculations, we show that the frequency dependence of the self-energy has a substantial impact on the ground state. Furthermore, we investigate the relation between the density-density interaction and the quasiparticle lifetime. During the course of our study, we will develop a saddle-point formulation of Schwinger-Dyson equations and present a new renormalization group scheme which is valid for all fermionic systems.