Particle-Hole Symmetry of Charge Excitation Spectra in the Paramagnetic Phase of the Hubbard Model

Vu Hung Dao, Raymond Frésard Normandie University, ENSICAEN, UNICAEN, CNRS, CRISMAT, 14000 Caen, France

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The Kotliar and Ruckenstein slave-boson representation of the Hubbard model allows to obtain an approximation of the charge dynamical response function resulting from the Gaussian fluctuations around the paramagnetic saddle-point in analytical form. Numerical evaluation in the thermodynamical limit yields charge excitation spectra consisting of a continuum, a gapless collective mode with anisotropic zero-sound velocity, and a correlation induced high-frequency mode at ω ≈ U. In this work we show that this analytical expression obeys the particle-hole symmetry of the model on any bipartite lattice with one atom in the unit cell. Other formal aspects of the approach are also addressed.

DOI: 10.12693/APhysPolA.133.336 PACS numbers: 71.10.Fd, 72.15.Nj, 71.30.+h