Multiloop functional renormalization group for general models

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...

A NUMERICAL RENORMALIZATION GROUP APPROACH FOR AN ELECTRON-PHONON INTERACTION

A finite chain calculation in terms of Hubbard X-operators is explored by setting up a vibronic Harniltonian. The model conveniently transformed into a form so that in the case of strong coupling a numerical renormalization group approach is applicable. To test the technique, a one particle Green function is calculated for the model Harniltonian

Renormalization Group Results for Lattice Surface Models

We study the phase diagram of statistical systems of closed and open interfaces built on a cubic lattice. Interacting closed interfaces can be written as Ising models, while open surfaces as Z(2) gauge systems. When the open surfaces reduce to closed interfaces with few defects, also the gauge model can be written as an Ising spin model. We apply the lower bound renormal-ization group (LBRG) tr...

Renormalization Group for Directed Sandpile Models

Following the lead of earlier researchers, we construct a real space renormalization group map for a class of self-organized critical models. We then test a series of quantitative predictions implied by this map against direct simulations of various models. The theory passes four tests, but apparently fails a fifth. We also find that the map has an interesting nongeneric property, suggesting a ...

Renormalization Group Renormalization Group