The Bogolubov generating functional method in statistical physics and “collective” variables transform within the grand canonical ensemble

We show that the Bogolubov generating functional method is a very effective tool for studying distribution functions of both equilibrium and nonequilibrium states of classical many-particle dynamical systems. In some cases the Bogolubov generating functionals can be represented by means of infinite Ursell –Mayer diagram expansions, whose convergence holds under some additional constraints on the statistical system under consideration. The classical Bogolubov idea to use the Wigner density operator transformation for studying the nonequilibrium distribution functions is developed, a new analytic nonstationary solution to the classical Bogolubov evolution functional equation is constructed.Доведено, що метод породжуючих функціоналів Боголюбова є досить ефективним для вивчення функцій розподілу рівноважних та нерівноважних станів класичних багаточастинкових динамічних систем. У деяких випадках породжуючі функціонали Боголюбова можна виразити через нескінченні розвинення діаграм Урселла - Мартіна, які збігаються при накладанні додаткових умов на розглядувані статистичні системи. Розвинуто класичну ідею Боголюбова про використання перетворення Вігнера оператора щільності для вивчення нерівноважних функцій розподілу та побудовано новий нестаціонарний розв'язок класичного рівняння еволюції функціонала Боголюбова

Macroscopic quantum state and high-temperature superconductivity in semi-localized 2D electron system with circular molecular orbits

Recently new type of high temperature superconductors is found which are characterized by the existence of circular molecular orbits in each unit site of 2D s/p electron system. In view of the characteristic, a new model of superfluidity is studied based on the coherent state where the zero-point oscillation of toroidal wave function causes a macroscopic quantum state. This model gives an estimation of the superfluidity transition temperature: Tc≈52-117 K for fcc C60, and Tc≈50-150 K for hole-doped MgB2

The Bogolubov representation of the polaron model and its completely integrable RPA-approximation

The polaron model in ionic crystal is studied in the Bogolubov representation using a special RPA-approximation. A new exactly solvable approximated polaron model is derived and described in detail. Its free energy at finite temperature is calculated analytically. The polaron free energy in the constant magnetic field at finite temperature is also discussed. Based on the structure of the Bogolubov unitary transformed polaron Hamiltonian there is stated a very important new result: the full polaron model is exactly solvable.Досліджено модель полярона в іонному кристалі в представленні Боголюбова, використовуючи особливе наближення хаотичних фаз. Виведено та описано нову точно розв'язну наближену модель полярона. Аналітично одержано вільну енергію такої моделі за ненульової температури. Розглянуто вільну енергію полярона в постійному магнітному полі за ненульової температури. На базі унітарного перетворення Боголюбова для поляронного гамільтоніана одержано важливий новий результат: повна модель полярона є точно розв'язною

The Relativistic Electrodynamics Least Action Principles Revisited: New Charged Point Particle and Hadronic String Models Analysis

The classical relativistic least action principle is revisited from the vacuum field theory approach. New physically motivated versions of relativistic Lorentz type forces are derived, a new relativistic hadronic string model is proposed and analyzed in detail.Comment: n/

Quantum theory of the far-off-resonance continuous-wave Raman laser: Heisenberg-Langevin approach

We present the quantum theory of the far-off-resonance continuous-wave Raman laser using the Heisenberg-Langevin approach. We show that the simplified quantum Langevin equations for this system are mathematically identical to those of the nondegenerate optical parametric oscillator in the time domain with the following associations: pump pump, Stokes signal, and Raman coherence idler. We derive analytical results for both the steady-state behavior and the time-dependent noise spectra, using standard linearization procedures. In the semiclassical limit, these results match with previous purely semiclassical treatments, which yield excellent agreement with experimental observations. The analytical time-dependent results predict perfect photon statistics conversion from the pump to the Stokes and nonclassical behavior under certain operational conditions

The Lagrangian and Hamiltonian analysis of some relativistic electrodynamics models and their quantization

The work is devoted to the study of the Lagrangian and Hamiltonian properties of some relativistic electrodynamics models and is a continuation of our previous investigations. Based on the vacuum field theory approach, the Lagrangian and Hamiltonian reformulation of some classical electrodynamics models is devised. The Dirac type quantization procedure, based on the canonical Hamiltonian formulation, is developed. Within the approach proposed in the work a possibility of the combined description both of electrodynamics and gravity is analyzed

Second order approximation for optical polaron in the strong couplin case

Consiglio Nazionale delle Ricerche (CNR). Biblioteca Centrale / CNR - Consiglio Nazionale delle RichercheSIGLEITItal

Uniform upper bounds in the Froehlich polaron theory

Consiglio Nazionale delle Ricerche (CNR). Biblioteca Centrale / CNR - Consiglio Nazionale delle RichercheSIGLEITItal

The linearized polaron model treated by the diagonalization method and the Green function method

SIGLEITItal