Author: Vieri Mastropietro

Title: Spin-Charge separation for a two-dimensional Flat Fermi surface

Abstract: Although Spin-Charge (SC) separation has been well established in one dimensional fermionic systems, the theoretical situation for two dimensions, the relevant case for describing high $T_c$ cuprates, is rather controversial. In this paper we consider a system of two-dimensional electrons with a flat Fermi Surface, and we prove that a weak interaction between electrons on the same sector produces SC separation. Our treatment is rigorous and based on novel methods introduced in the framework of Constructive Renormalization Group: SC separation emerges from the anomalies in the Ward Identities obtained from local phase transformations depending on the Fermi surface side.