Kinematic formation of the pseudogap spectral properties in a spatially   homogeneous strongly correlated electron system
  It is shown that the kinematic interaction caused by the quasi-Fermi character of commutation relations for operators of the atomic representation can induce pseudogap behavior of the spectral characteristics of an ensemble of Hubbard fermions. Mathematically, the presence of the kinematic interaction manifests itself in modification of the faithful representation of a single-particle Green's function of Hubbard fermions $D(\textbf{k},i\omega_n)$, which involves, apart from self-energy operator $\Sigma_L(\textbf{k},i\omega_n)$, strength operator $P(\textbf{k},i\omega_n)$. It is important that the strength operator enters both the numerator and the denominator of the exact expression for $D(\textbf{k},i\omega_n)$. The kinematic interaction, therefore, not only renormalizes the spectrum of elementary excitations but significantly affects their spectral weight. It results in strong modulation of spectral intensity $A(\textbf{k},\omega)$ occurring on a Fermi contour. Calculations of the spectral properties for the $t-J$ model in the one-loop approximation yield good quantitative agreement with the ARPES data obtained on cuprate superconductors. 
Valery V. Val'kov, Alexander A. Golovnya, Maxim M. Korovushkin
cond-mat.str-el