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TT: Fachverband Tiefe Temperaturen

TT 86: Correlated Electrons: (General) Theory 2

TT 86.6: Vortrag

Donnerstag, 19. März 2015, 10:45–11:00, H 3005

Summing parquet diagrams via the functional renormalization group: x-ray problem revisited¹ — •Philipp Lange, Casper Drukier, Anand Sharma, and Peter Kopietz — Institut für Theoretische Physik, Universität Frankfurt

We present a simple and efficient method for summing so-called parquet diagrams of fermionic many-body systems with competing instabilities using the functional renormalization group. Our method is based on partial bosonization of the interaction using multi-channel Hubbard-Stratonovich transformations. A straightforward truncation of the resulting flow equations retaining only the frequency-independent parts of the two-point and three-point functions amounts to solving coupled Bethe-Salpeter equations for the effective interaction to leading logarithmic order. We apply our method to the x-ray problem and derive the singular frequency dependence of the x-ray response function and the particle-particle susceptibility. Our method can be applied to various other problems involving strong fluctuations in more than one scattering channel.

[1] G. D. Mahan, Phys. Rev. 163, 612 (1967).