Fermionic functional renormalization group flows into phases with broken symmetry

Roland Gersch, Carsten Honerkamp A, D. Rohe +1 more

O. Lauscher, Manfred Salmhofer B, Carsten Honerkamp A +1 more

Carsten Honerkamp A, Manfred Salmhofer B

We describe how the fermionic functional renormalization group (fRG) flow of a Cooper+forward scattering problem can be continued into the superconducting state. This allows us to reproduce from the fRG flow the fundamental equations of the Eliashberg theory for superconductivity at all temperatures including the symmetry-broken phase. We discuss possible extensions of this approach like the inclusion of vertex corrections.

Carsten Honerkamp A

We review recent developments in functional renormalization group (RG) methods for interacting fermions. These approaches aim at obtaining an unbiased picture of competing Fermi liquid instabilities in the low-dimensional models like the two-dimensional Hubbard model. We discuss how these instabilities can be approached from various sides and how the fermionic RG flow can be continued into phases with broken symmetry.

Andreas Sinner, N. Hasselmann, Peter Kopietz

Peter Kopietz, Lorenz Bartosch, Florian Schütz