Journal of Experimental and Theoretical Physics最新文献

In this review devoted to analysis of the mechanisms and characteristics of recording and relaxation of elementary spatial structures in polymer films and solutions colored by organic dyes, the basic principles of holographic analysis, the experimental technique and measuring methods, and some applications are considered consistently. The results of investigation of the dynamics of laser recording and subsequent relaxation of spatially inhomogeneous concentration and thermal structures in polymer films and solutions under their initiation by axisymmetric or sinusoidally modulated light field are reported. The probing beam diffraction on a nonstationary axisymmetric structure and the kinetics of the angular dependence of the diffracted probing beam during its transmission through and amplitude concentration or phase thermal grating is considered and a theoretical model that successfully describes the experimental results is proposed. For diffusive relaxation of holographic gratings recorded in biopolymer solutions under laser-induced fragmentation of molecular chains, the dispersion of macromolecule fragment lengths is taken into account. The problems of recording of stationary phase gratings and anthracene-containing polymer media in accordance with the oxidation mechanism are considered; for this mechanism, the effect of concentrations and mutual distribution of reagents on the grating recording process is assessed, and the mechanisms of the grating profile distortions are determined. The features of formation of the relief–phase gratings in polymer media with the laser-induced swelling are considered and the corresponding theoretical models ensuring good agreement with experiment are proposed. Holographic methods are employed for studying the kinetics of some molecular reactions; it is shown, for example, that during static annihilation of triplet centers, the grating profile is deformed, which is manifested in the kinetics of diffraction maxima. In recording of a grating in a disperse medium on triplet centers, in the case of their active annihilation, fluctuations of occupation numbers of microcavities are suppressed, while in the case of a diffusion-accelerated reaction, this effect becomes even more significant.

A density functional theory (PBE-GGA and PBE-GGA-D3) study on the adsorption of H, C, O, OH, CO, COOH, HCOO, and HCOOH on the perfect and defective Au(110) surfaces is presented. The thermochemical decomposition of HCOOH on the perfect and defective Au(110) surfaces has been also examined by using the PBE-GGA functional. The adsorption energies, the preferred adsorption sites, the structural parameters, the work function change and the dipole moment change were determined. The Local Density of States (LDOS) have also been calculated. The DFT calculations have shown that, HCOOH weakly adsorbs on the Au surfaces, with the PBE-GGA functional, whereas, HCOOH is not stable with the PBE-GGA-D3 functional. Results obtained revealed that the HCOOH decomposition is endothermic on the perfect Au(110) surface. Whereas it is exothermic on the defective Au surfaces. This suggests that the presence of defects (Au adatom and a vacancy) may facilitate the fragmentation process. HCOOH thermochemistry calculations have also shown that the COOH dehydrogenation is more difficult than that of HCOO. Otherwise, COOH is easier to make than HCOO on the Au(110) surfaces.

This study investigates the influence of citrate-capped gold nanoparticles (AuNPs) dispersed in varying concentrations within the liquid crystal compound 4-decyloxybenzoic acid (10oba) for modulation of optical properties. Incorporation of AuNPs, the liquid crystalline (LC) phases remained stable, their transition temperatures were approximately same with complementary methods. A modified spectrometer was employed to measure birefringence across multiple wavelengths, revealing a progressive increase in optical properties with higher AuNP concentrations. To evaluate the orientation ordering within the system, several theoretical models—including the Kuczynski internal field model, Vuks model, Haller’s extrapolation, and effective geometry parameter method—were applied to determine the order parameter. All theoretical models also consistently indicate an enhancement in optical properties with increasing AuNP content. This trend is attributed due to strengthened van der Waals interactions between the LC molecules and the gold nanoparticles, which promote improved molecular alignment and optical properties within the mesophase. These findings emphasize the potential of nanoparticle-doped LC systems for modulating optical properties useful for light dependent applications.

Cassini’s measurements suggest that ice bodies of Saturn’s visible dense rings have diamagnetic properties. The James Webb space telescope (JWST) confirmed the existence of water around forming planets and showed that the magnetic field plays an important role in the formation of planets. It follows that Saturn’s visible dense rings could arise from the ice bodies of a protoplanetary cloud with the radius of the Roche limit under the combined action of a diamagnetic expulsion produced by Saturn’s magnetic field together with Saturn’s gravitational and centrifugal forces. As a result, Kepler’s orbits of the ice bodies of the protoplanetary cloud move into the plane of Saturn’s equator and form a highly compressed stable system of the visible dense rings with separate individual ice bodies. Due to magnetization by Saturn’s magnetic field, the magnetic moments of ice bodies align in the same orientation, causing them to repel and separate. Ice bodies are also attracted to each other due to their own gravity. At the balance of all the forces, the ice bodies remain at an equilibrium distance from each other. This provides an important proof for J.C. Maxwell’s discovery made in 1856 that Saturn’s visible dense rings are not continuous, but are composed of individual bodies. The presented theory offers an explanation for the origin of Saturn’s visible dense rings and their structure as observed by the Cassini probe in 2004–2017. It can also improve purely gravitational models of the origin of Saturn’s visible dense rings, which can show only how additional ice could penetrate the visible dense rings, but cannot convincingly explain their origin and structure.

The aim of this work is a numerical study of the features of magnetoplasmonic effects arising from the diffraction of THz waves on graphene metasurfaces in external magnetic fields. The advantage of graphene over conventional plasmonic materials used in plasmonic and magnetooptical devices is the high sensitivity of surface magnetoplasmon–polaritons to external magnetic fields since the cyclotron frequency is comparable to the plasmon frequency in the THz and far IR ranges. Numerical study of magnetoplasmonic resonances of graphene metasurfaces depending on the induction of an external magnetic field and modeling of 3D e-Field scattering patterns from an element of a graphene metasurface (rectangular graphene nanoribbon) has been carried out using the CST MWS software package. To solve the electrodynamic diffraction problem using MWS CST, a method has been chosen to analyze a graphene metasurface (an infinite periodic 2D structure) by applying periodicity conditions that reduce the problem for an infinite structure to analysis of one period. The results of modeling the 3D e-Field scattering pattern from an element of a magnetically biased graphene metasurface (a rectangular graphene nanoribbon) of incident TEM-waves of p- and s-polarization have been obtained for the vertical E_y and horizontal E_x components of the diffracted field at magnetoplasmon resonance frequencies in the THz range. Analysis of magnetoplasmonic effects has been performed based on the calculation of the ratio of the diffracted field components and the axial ratio at the points of cross section (φ = 0°) of the main lobe of the 3D e-Field scattering pattern for the normal incidence of TEM-waves of p- and s-polarization. The results of the numerical study of the performances of the magnetically biased graphene metasurfaces show that magnetoplasmonic effects are observed at resonance frequencies; i.e., there appears of another component of the diffracted field, which is orthogonal to the exciting one, as well as the magnetooptical effects of rotation of the polarization plane of the transmitted wave (Faraday effect), rotation of the polarization plane and the emergence of ellipticity of a linearly polarized wave during its reflection from the graphene surface (magnetooptical Kerr effect), depending on the magnitude of the external magnetic field.

We present an enhanced Fisher information framework for neutrino oscillation parameter estimation that incorporates comprehensive treatment of systematic uncertainties and experimental correlations, achieving cross-validation stability ({{S}_{{{text{CV}}}}} > 0.85). Building upon standard statistical inference methods, our approach provides improved precision estimates for oscillation parameters through rigorous modeling of systematic effects, energy-dependent correlations, and detector-specific uncertainties. Validation against T2K and NOvA experimental data demonstrates conservative precision estimates of 6.8% for (Delta m_{{31}}^{2}) in T2K and 7.5% in NOvA, representing a 15–25% improvement in uncertainty quantification compared to simplified treatments. The framework includes cross-validation analysis, sensitivity studies, and practical tools for experimental design optimization. Applications to future experiments suggest precision improvements of 30–40% for DUNE through optimized statistical analysis. This work provides the neutrino physics community with robust, validated tools for precision parameter estimation and experimental planning.

Using the approach developed by one of the authors, possible values of solar electron neutrino deficit has been obtained. The results can be verified in future experiments. The prospects in developing the computational method have been indicated.

Background. The aim of the work is to solve the inverse problem of diffraction on flat objects. Materials and methods. The initial problem is reduced to solving an integral equation. This equation is solved numerically. A modern two-step approach has been used to solve the inverse problem. Various types of field nonlinearity functions are used to simulate a nonlinear process. Results. A numerical method for solving the problem of diffraction on flat objects is implemented programmatically. Graphical images illustrating the value of the permittivity inside the body for the initial problem and the reconstructed values are presented. Graphs of convergence of the iterative process of modeling a nonlinear field are shown. The results of solving the problem taking into account different values of the nonlinearity parameters are presented. Conclusions. A numerical method for solving the problem is proposed and implemented, and comparative results are obtained. This approach to the solution can also be used for more complex nonlinear problems.

The conditions of soliton formation in a liquid crystal layer for generation of a pair of photons in an entangled quantum state (biphotons) during quantum calculations are considered. The geometrical dimensions of the soliton generated by a pulse of optical radiation, its dynamics and stability are estimated by using the knowledge of the liquid crystal physical parameters as well as its non-linear optical properties. The possibility of overlapping of optical solitons neighboring in space or time (or regions inside the liquid crystal layer, in which the deformation induced by the light wave field from successive light pulses occurs) is considered. In nematic liquid crystals (LCs), it is possible to obtain single solitons with spatial size of several tens of micrometers and less, the formation time from fractions of a millisecond to tens of milliseconds, and the existence time from fractions of the millisecond to hundreds of milliseconds. On this basis, it is possible to “encode” entangled states with a high level of signal distinction and to carry out quantum calculations.