RENORMALIZATION GROUP ANALYSIS OF A TWO-DIMENSIONAL INTERACTING ELECTRON SYSTEM

2001 ◽  
Vol 16 (11) ◽  
pp. 1889-1898
Author(s):  
WALTER METZNER
Keyword(s):  
Renormalization Group ◽  
Group Analysis ◽  
Interaction Strength ◽  
Electron System ◽  
Flow Equation ◽  
Group Method ◽  
Model Parameters ◽  
Two Dimensional ◽  
Renormalization Group Analysis ◽  
Effective Interactions

We describe a Wick ordered functional renormalization group method for interacting Fermi systems, where the complete flow from the bare action of the microscopic model to the effective low-energy action is obtained from a differential flow equation. We apply this renormalization group approach to a prototypical two-dimensional lattice electron system, the Hubbard model on a square lattice. The flow equation for the effective interactions is evaluated numerically on 1-loop level. The effective interactions diverge at a finite energy scale which is exponentially small for small bare interactions. To analyze the nature of the instabilities signalled by the diverging interactions we compute the flow of the singlet superconducting susceptibilities for various pairing symmetries and also charge and spin density susceptibilities. Depending on the choice of the model parameters (hopping amplitudes, interaction strength and band-filling) we find antiferromagnetic order or d-wave superconductivity as leading symmetry breaking instability.

RENORMALISATION GROUP ANALYSIS OF THE TWO-DIMENSIONAL HUBBARD MODEL: SPIN CORRELATIONS AND D-WAVE SUPERCONDUCTIVITY

2003 ◽  
Vol 17 (28) ◽  
pp. 5279-5288
Author(s):  
W. METZNER
Keyword(s):  
Hubbard Model ◽  
Spin Density ◽  
Density Wave ◽  
Group Analysis ◽  
Interaction Strength ◽  
Renormalisation Group ◽  
Model Parameters ◽  
Two Dimensional ◽  
Effective Interactions ◽  
D Wave

The repulsive two-dimensional Hubbard model is analysed within a functional renormalisation group (RG) approach. The flow equation for the effective interactions is evaluated on 1-loop level. The effective interactions diverge at a finite energy scale which is exponentially small for small bare interactions. To analyse the nature of the instabilities signalled by the diverging interactions, we compute the flow of the superconducting susceptibilities for various pairing symmetries and also charge and spin density susceptibilities. Depending on the choice of the model parameters (hopping amplitudes, interaction strength and band-filling) we find spin density wave instabilities or d-wave superconductivity as leading instability close to half-filling. This calculation establishes the existence of d-wave superconductivity in the Hubbard model beyond doubt.

scholarly journals DOMAIN WALL RENORMALIZATION GROUP ANALYSIS OF TWO-DIMENSIONAL ISING MODEL

2009 ◽  
Vol 23 (18) ◽  
pp. 3739-3751 ◽  
Author(s):  
KEN-ICHI AOKI ◽  
TAMAO KOBAYASHI ◽  
HIROSHI TOMITA
Keyword(s):  
Renormalization Group ◽  
Ising Model ◽  
Domain Wall ◽  
Domain Walls ◽  
Group Analysis ◽  
Coarse Graining ◽  
Group Method ◽  
Two Dimensional ◽  
Renormalization Group Analysis ◽  
Renormalization Transformation

Using a recently proposed new renormalization group method (tensor renormalization group), we analyze the Ising model on the two-dimensional square lattice. For the lowest-order approximation with two-domain wall states, it realizes the idea of coarse graining of domain walls. We write down explicit analytic renormalization transformation and prove that the picture of the coarse graining of the physical domain walls does hold for all physical renormalization group flows. We solve it to get the fixed point structure and obtain the critical exponents and the critical temperature. These results are very near to the exact values. We also briefly report the improvement using four-domain wall states.

A renormalization group analysis of lattice models of two-dimensional membranes

1989 ◽  
Vol 55 (1-2) ◽  
pp. 29-85 ◽  
Author(s):  
Jan Ambj�rn ◽  
Bergfinnur Durhuus ◽  
J�rg Fr�hlich ◽  
Th�rdur J�nsson
Keyword(s):  
Renormalization Group ◽  
Group Analysis ◽  
Lattice Models ◽  
Two Dimensional ◽  
Renormalization Group Analysis

RENORMALIZATION GROUP METHODS IN CONSTRUCTIVE FIELD THEORIES

2000 ◽  
Vol 14 (12n13) ◽  
pp. 1363-1398
Author(s):  
HIROSHI WATANABE
Keyword(s):  
Renormalization Group ◽  
Group Analysis ◽  
Group Method ◽  
Coupling Region ◽  
Renormalization Group Analysis ◽  
New Approach ◽  
Group Methods ◽  
Technical Details ◽  
Hierarchical Approximation

Mathematical construction of quantum field theory is reviewed with emphasis on the conceptual structure of the construction and on the role of rigorous renormalization group analysis without technical details. After explaining a rigorous formulation of a renormalization group method in a weak coupling region, a new approach in a strong coupling region is proposed in the context of the hierarchical approximation. An idea of proving triviality in d≥4 dimensions utilizing this new proposal concludes this review.

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