paper

Absence of Luttinger's Theorem due to Zeros in the Single-Particle Green Function

arXiv:1207.4201 · doi:10.1103/PhysRevLett.110.090403

Abstract

We show exactly with an SU(N) interacting model that even if the ambiguity associated with the placement of the chemical potential, , for a T=0 gapped system is removed by using the unique value , Luttinger's sum rule is violated even if the ground-state degeneracy is lifted by an infinitesimal hopping. The failure stems from the non-existence of the Luttinger-Ward functional for a system in which the self-energy diverges. Since it is the existence of the Luttinger-Ward functional that is the basis for Luttinger's theorem which relates the charge density to sign changes of the single-particle Green function, no such theorem exists. Experimental data on the cuprates are presented which show a systematic deviation from the Luttinger count, implying a breakdown of the electron quasiparticle picture in strongly correlated electron matter.

Published version with supplemental material rebutting the recent criticism that our theorem fails if the ground-state degeneracy is lifted

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