We study the nonequilibrium quench dynamics of a mixed Sachdev-Ye-Kitaev model, with competing two-body random interactions leading to maximally chaotic non-Fermi liquid and single body term which dominates at low temperatures leads Fermi behavior. For different protocols, including sudden switching interaction double we solve large $N$ real-time Dyson equation on Keldysh contour compute Green'...

We study electric, thermal, and thermoelectric conductivities in the vicinity of a z = 2 superconductor-diffusive metal transition in two dimensions, both in the high and low frequency limits. We find violation of the Wiedemann-Franz law and a dc thermoelectric conductivity α that does not vanish at low temperatures, in contrast to Fermi liquids. We introduce a Langevin equation formalism to st...

New calculation reveals that E is constant in a thin layer across the Fermi surface, befitting the definition of energy gap parameter, ∆ varies dramatically. The BCS self-consistent equation has a simple and exact solution, showing that the well-known ratio 3.5 must be replaced by 4. A simple formula is found to estimate energy gap from first principles with reasonable accuracy, useful to the c...

The thermodynamic properties of heated nuclear matter are explored using an exactly solvable canonical ensemble model. This model reduces to the results of an ideal Fermi gas at low temperatures. At higher temperatures, the fragmentation of the nuclear matter into clusters of nucleons leads to features that resemble a Bose gas. Some parallels of this model with the phenomena of Bose condensatio...

Around one second after the big bang, neutrino decoupling and e-e annihilation distort the Fermi-Dirac spectrum of neutrino energies. Assuming neutrinos have masses and can mix, we compute the distortions using nonequilibrium thermodynamics and the Boltzmann equation. The flavor behavior of neutrinos is studied during and following the generation of the distortion. Accepted for publication in P...

The screened quasi-relativistic potential is used for describing spin-orbit splitting in PJ waves of quark-antiquark system. Fermi-Breit equation is solved numerically in configuration interaction approximation. This approximation takes into account the mixing of wave functions up to fifth order and corrects substantially perturbation calculations. The nature of potentials Lorentz transformatio...

The major problem posed by the Fermi-Pasta-Ulam work was the relaxation (thermalization) of a many-body system. We review two approaches to this problem, the ergodic theory and Langevin (stochastic) equation ones, which have been applied for the description of statistical mechanics of stellar systems. Among the particular problems that we consider, are 1-dimensional long-range interacting syste...

We study the periodic Hartree-Fock model used for the description of electrons in a crystal. The existence of a minimizer was previously shown by Catto, Le Bris and Lions (Ann. Inst. H. Poincaré Anal. Non Linéaire 18 (2001), no. 6, 687–760). We prove in this paper that any minimizer is necessarily a projector and that it solves a certain nonlinear equation, similarly to the atomic case. In part...

For the iron-based high Tc superconductor LaFeAsO1−xFx, we construct a minimal model, where all of the five Fe d bands turn out to be involved. We then investigate the origin of superconductivity with a five-band random-phase approximation by solving the Eliashberg equation. We conclude that the spin fluctuation modes arising from the nesting between the disconnected Fermi pockets realise, basi...

Symmetric nuclear matter is studied within the conserving, self-consistent T -matrix approximation. This approach involves off-shell propagation of nucleons in the ladder diagrams. The binding energy receives contributions from the background part of the spectral function, away form the quasiparticle peak. The Fermi energy at the saturation point fulfills the Hugenholz-Van Hove relation. In com...