Perturbation study of nonequilibrium quasiparticle spectra in an infinite-dimensional Hubbard lattice

A model for nonequilibrium dynamical mean-field theory is constructed for the infinite-dimensional Hubbard lattice. We impose nonequilibrium by expressing the physical orbital as a superposition of a left (L)-moving and right (R)-moving electronic state with the respective chemical potentials mu(L) and mu(R). Using the second-order iterative perturbation theory we calculate the quasiparticle properties as a function of the chemical potential bias between the L and R movers, i.e., Phi = mu(L)-mu(R). The evolution of the nonequilibrium quasiparticle spectrum is mapped out as a function of the bias and temperature. The quasiparticle states with the renormalized Fermi-energy scale epsilon(0)(QP) disappear at Phi similar to epsilon(0)(QP) in the low-temperature limit. The second-order perturbation theory predicts that in the vicinity of the Mott-insulator transition at the Coulomb-parameter U = U-c, there exists another critical Coulomb-parameter U-d (