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We use the Matsubara functional renormalization group (FRG) to describe electronic correlations within the single impurity Anderson model. In contrast to standard FRG calculations, we account for the frequency-dependence of the two-particle…

Strongly Correlated Electrons · Physics 2009-11-13 C. Karrasch , R. Hedden , R. Peters , Th. Pruschke , K. Schönhammer , V. Meden

Fermionic functional renormalization group (FRG) is applied to describe the superfluid phase transition of the two-component fermionic system with attractive contact interaction. Connection between the fermionic FRG approach and the…

Quantum Gases · Physics 2014-08-19 Yuya Tanizaki , Gergely Fejős , Tetsuo Hatsuda

We provide a detailed presentation of the functional renormalisation group (FRG) approach for weakly-interacting Bose-Bose mixtures, including a complete discussion on the RG equations. To test this approach, we examine thermodynamic…

Quantum Gases · Physics 2022-01-21 Felipe Isaule , Ivan Morera

Functional renormalization group (FRG) is applied to the three-body scattering problem in the two-component fermionic system with an attractive contact interaction. We establish a new and correct flow equation on the basis of FRG and show…

Quantum Gases · Physics 2013-11-05 Yuya Tanizaki

We study the application of the exact renormalisation group to a many-fermion system with a short-range attractive force. We introduce a boson field to describe pairing effects, and take a simple ansatz for the effective action. We derive a…

High Energy Physics - Phenomenology · Physics 2016-09-06 Michael C. Birse , Boris Krippa , Judith A. McGovern , Niels R. Walet

Approximated functional renormalization group (FRG) equations lead to regulator-dependent $\beta$-functions, in analogy to the scheme-dependence of the perturbative renormalization group (pRG) approach. A scheme transformation redefines the…

High Energy Physics - Theory · Physics 2024-07-16 S. Hariharakrishnan , U. D. Jentschura , I. G. Marian , K. Szabo , I. Nandori

We present a functional renormalization group (fRG) formalism for interacting fermions on lattices that captures the flow into states with commensurate spin-density wave order. During the flow, the growth of the order parameter is fed back…

Strongly Correlated Electrons · Physics 2014-07-31 Stefan A. Maier , Andreas Eberlein , Carsten Honerkamp

The conceptual framework provided by the functional Renormalization Group (fRG) has become a formidable tool to study correlated electron systems on lattices which, in turn, provided great insights to our understanding of complex many-body…

Computational Engineering, Finance, and Science · Computer Science 2016-11-02 Julian Lichtenstein , Jan Winkelmann , David Sánchez de la Peña , Toni Vidović , Edoardo Di Napoli

We study a pseudogap region of the mixed boson fermion system using a recent formulation of the renormalization group technique through the set of infinitesimal unitary transformations. Renormalization of fermion energies gives rise to a…

Superconductivity · Physics 2016-08-31 T. Domanski , J. Ranninger

We study the symmetric Anderson-Holstein (AH) model at zero temperature with Wilson's numerical renormalization group (NRG) technique to study the interplay between the electron-electron and electron-phonon interactions. An improved method…

Strongly Correlated Electrons · Physics 2009-11-07 Gun Sang Jeon , Tae-Ho Park , Han-Yong Choi

Within the Functional Renormalisation Group (FRG) approach, we present a fluid-dynamical approach to solving flow equations for models living in a multi-dimensional field space. To this end, the underlying exact flow equation of the…

Statistical Mechanics · Physics 2024-12-23 Niklas Zorbach , Adrian Koenigstein , Jens Braun

Functional renormalization group (FRG) has become a diverse and powerful tool to derive effective low-energy scattering vertices of interacting many-body systems. Starting from a non-interacting expansion point of the action, the flow of…

Strongly Correlated Electrons · Physics 2014-01-22 Johannes Reuther , Ronny Thomale

The functional renormalization group (FRG) has been used widely to investigate phase diagrams, in particular the one of the two-dimensional Hubbard model. So far, the study of one-dimensional models has not attracted as much attention. We…

Strongly Correlated Electrons · Physics 2018-06-18 Lisa Markhof , Björn Sbierski , Volker Meden , Christoph Karrasch

We study transport properties of quantum impurity systems using the functional renormalization group. The latter is an RG-based diagrammatic tool to treat Coulomb interactions in a fast and flexible way. Prior applications, which employed a…

Strongly Correlated Electrons · Physics 2010-09-21 C. Karrasch

We extend the recently introduced single-boson exchange formulation to the computation of the self-energy from the Schwinger--Dyson equation (SDE). In particular, we derive its expression both in diagrammatic and in physical channels. The…

The pseudofermion functional renormalization group (pffRG) is a computational method for determining zero-temperature phase diagrams of frustrated quantum magnets. In a recent methodological advance, the commonly employed Katanin truncation…

Strongly Correlated Electrons · Physics 2022-07-04 Marc K. Ritter , Dominik Kiese , Tobias Müller , Fabian B. Kugler , Ronny Thomale , Simon Trebst , Jan von Delft

The functional renormalization group (FRG) provides a flexible tool to study correlations in low-dimensional electronic systems. In this paper, we present a novel FRG approach to the steady-state of quantum wires out of thermal equilibrium.…

Strongly Correlated Electrons · Physics 2020-12-08 Christian Klöckner , Dante Marvin Kennes , Christoph Karrasch

Functional renormalisation group approach is applied to a imbalanced many- fermion system with a short-range attractive force. Composite boson field is introduced to describe the pairing between different flavour fermions. A set of…

Quantum Gases · Physics 2015-06-22 Boris Krippa

The functional renormalization group (fRG) approach has the property that, in general, the flow equation for the two-particle vertex generates $\mathcal{O}(N^4)$ independent variables, where $N$ is the number of interacting states (e.g.…

Strongly Correlated Electrons · Physics 2014-01-24 Florian Bauer , Jan Heyder , Jan von Delft

We present a functional renormalization group (fRG) study of the two dimensional Hubbard model, performed with an algorithmic implementation which lifts some of the common approximations made in fRG calculations. In particular, in our fRG…

Strongly Correlated Electrons · Physics 2019-10-23 Agnese Tagliavini , Cornelia Hille , Fabian B. Kugler , Sabine Andergassen , Alessandro Toschi , Carsten Honerkamp