Critical Exponents of Strongly Correlated Fermion Systems from Diagrammatic Multi-Scale Methods

Abstract

Self-consistent dynamical approximations for strongly correlated fermion systems are particularly successful in capturing the dynamical competition of local correlations. In these, the effect of spatially extended degrees of freedom is usually only taken into account in a mean field fashion or as a secondary effect. As a result, critical exponents associated with phase transitions have mean field character. Here, we demonstrate that diagrammatic multi-scale methods anchored around local approximations are indeed capable of capturing the non mean-field nature of the critical point of the lattice model encoded in a non-vanishing anomalous dimension, and to correctly describe the transition to mean field like behavior as the number of spatial dimensions increases.

5+4 pages, 5+2 figures