Vol 169, No 3 (2026)

We investigate the influence of the amplitude and frequency of thermal vibrations of atomic scatterers on the nature of radiative transfer in optically dense ensembles of impurity centers with impurity centers high concentrations. The role of collective effects due to dipole-dipole interatomic interactions is examined by studying the transmittance of quasi-resonant radiation. It is shown that at high root-mean-square atomic velocities the effect of strong (Anderson) light localization which occurs at small vibration amplitudes, changes into diffusive transport as these amplitudes increase. Changing the vibration frequency can either enhance or weaken collective effects. There is a frequency range for which the sensitivity of collective effects to vibrational motion is maximal.

The paper proposes an original method for reconstructing the parameters of galactic sources that give rise to features in the observed energy spectra of cosmic rays, as well as the environment in which the acceleration and propagation of particles occurs. The key element of the proposed approach is the model of non-classical diffusion of cosmic rays developed by the authors, which generalizes the Ginzburg – Syrovatsky normal diffusion model to the case of particle propagation in a highly inhomogeneous interstellar medium with an intermittent magnetic field. It is shown that the most important results of the non-classical diffusion model, namely, breaks in the observed spectrum that arise naturally without using additional assumptions, power-law asymptotics before and after the breaks, and the soft spectrum of particle generation in sources, make it possible to describe the spectral features established in the ATIC-2, PAMELA, AMS-02, NUCLEON, DAMPE, CALET, and LHAASO experiments in a self-consistent manner. A joint analysis of experimental data and the results of the non-classical diffusion model leads to the conclusion that the sources are not instantaneous, the key role in the particle acceleration processes is played by interactions with inhomogeneities of the medium (transient formations in the acceleration region, Levy traps), the main stage of spectrum formation occurs at the stage when the compression ratio of the shock waves in supernova remnants is approximately 3.1.

The single crystals of the layered organic conductor κ-BEDT-TTF₂Cu₂(CN)₃ were studied by X-ray diffraction and X-ray photoemission spectroscopy. The electronic structure of the conducting BEDT-TTF₂ layer and its Fermi surface details were analyzed by quantum chemical calculations within the DFT level theory based on structure model of the isolated positively charged conducting layers in a virtual charge compensation medium. Although the accepted stoichiometry for the κ-salts corresponds to the half-filled band structure model with a charge transfer level of q = 0.5 for the dimers [BEDT-TTF₂]^2q+, it was found that, for the crystals studied, minimum of the corrections to the system's total energy reaches a minimum at q = 0.488. This theoretically found charge reduction in the cationic conducting layer is presumably associated with the presence of positively charged impurities within the anion layer. Indeed, X-ray photoemission spectroscopy measurements taken in this work clearly show the presence of Cu²⁺ impurities, which reduce the average negative charge of the anion layer and, consequently, the positive charge of the layer of cationic conducting dimers. The consequences of this result for the conducting properties of the crystal are also discussed.

The dynamics of diffusing particles in media with absorbing traps under an external electric field is studied via numerical simulations in spaces of different dimensionality: one-, two-, and three-dimensional. It is shown that at long times, the electric-field-induced drift becomes the dominant mechanism governing the temporal asymptotics of the survival probability. The dependencies of the characteristic exponential decay time on trap concentration and electric field strength are determined. A transition from particle localization to a sub-drift regime, analogous to a second-order phase transition, is revealed. The results confirm the applicability of the scaling approach to the particle capture problem in an electric field.

We investigate the possibility of the emergence of ultra-complex conductivity diagrams in the nearly free electron approximation for metals with cubic symmetry. Estimates show that the emergence of such diagrams requires the Fermi level to fall into extremely narrow energy intervals within the conduction band. In our view, this circumstance is mostly due to the high symmetry and the simplest analytical form of the dispersion relations ε(p) under consideration.

Transport processes in open quantum systems (OQS) attract significant interest due to a wide range of applications in various fields of quantum technologies. In this paper, we consider a fermion OQS with a quadratic Hamiltonian interacting with reservoirs that have different temperatures and chemical potentials. The interaction of the OQS with the reservoirs leads to transitions between the OQS’s levels which are accompanied by the appearance of energy, particle, and heat flows, that depend on the frequency differences between the corresponding levels. It is shown that the directions of these flows are determined by the weighted occupancy of the reservoirs, where weight coefficients are determined by the rates of transitions between the corresponding levels. Using the example of two reservoirs, the presence of extrema in the achieved flows and their sign alternation are shown. The presence of OQS thermal conductivity maxima at certain frequency differences is shown. The influences of reservoir dimensions on stationary flows and thermal conductivity of the OQS are investigated. It is shown that by controlling the rate of dissipation into one of the OQS’s reservoirs, it is possible to control the flows of energy, particles, and heat into other reservoirs through a change in the weighted occupancy.

В связи с непредвиденными обстоятельствами произведена замена DOI статей с префиксом Российской академии наук за 2025 год. Во третьем выпуске ЖЭТФ за 2026 год размещена информация о замене цифрового идентификатора на действующий DOI.