Absence of Luttinger's theorem due to zeros in the single-particle Green function

• Published in: Physical review letters Vol. 110; no. 9; p. 090403
• Main Authors: Dave, Kiaran B, Phillips, Philip W, Kane, Charles L
• Format: Journal Article
• Language: English
• Published: United States 28.02.2013
• ISSN: 1079-7114
• DOI: 10.1103/physrevlett.110.090403

We show exactly with an SU(N) interacting model that even if the ambiguity associated with the placement of the chemical potential, μ, for a T=0 gapped system is removed by using the unique value μ(T→0), Luttinger's sum rule is violated even if the ground-state degeneracy is lifted by an infinitesimal hopping. The failure stems from the nonexistence 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.