Renormalized functional renormalization group

The renormalized and Renormalization–Group invariant Hartree–Fock approximation

We study the renormalization problem for the Hartree–Fock approximation of the O(N)−invariant φ model in the symmetric phase and show how to systematically improve the corresponding diagrammatic resummation to achieve the correct renormalization properties of the effective field equations, including Renormalization–Group invariance with the one–loop beta function. These new Hartree–Fock dynamic...

Cluster Functional Renormalization Group

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 the RG parameter Λ allows to trace the evolution of the effective one-particle and two-particle vertices towards low energies by taking into account the vertex...

Renormalization Group Renormalization Group

Ising exponents from the functional renormalization group

We study the 3d Ising universality class using the functional renormalization group. With the help of background fields and a derivative expansion up to fourth order we compute the leading index, the subleading symmetric and antisymmetric corrections to scaling, the anomalous dimension, the scaling solution, and the eigenperturbations at criticality. We also study the cross correlations of scal...

Fermionic Functional Integrals and the Renormalization Group

The Renormalization Group is the name given to a technique for analyzing the qualitative behaviour of a class of physical systems by iterating a map on the vector space of interactions for the class. In a typical non-rigorous application of this technique one assumes, based on one’s physical intuition, that only a certain finite dimensional subspace (usually of dimension three or less) is impor...