SKM 2023 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 5: Correlated Electrons: Method Development

TT 5.3: Vortrag

Montag, 27. März 2023, 10:00–10:15, HSZ 204

Functional renormalization group without functional integrals — Peter Kopietz, Rüdiger Krämer, and •Andreas Rückriegel — Institut für Theoretische Physik, Universität Frankfurt, Max-von-Laue Str. 1, 60438 Frankfurt

We show that exact functional renormalization group (FRG) flow equations for quantum systems can be derived directly within a Hamiltonian operator formalism without using functional integrals. This can be useful for teaching FRG methods to students unfamiliar with functional integrals and also opens new possibilities for applying FRG methods to quantum systems with projected Hilbert spaces such as quantum spin models or strongly interacting fermionic lattice models. In particular, by representing the Hubbard model and the t−J-model in terms of so-called Hubbard X-operators we construct a new strong-coupling FRG approach to these models.