International Journal of Theoretical Physics最新文献

{"title":"New Nonlinear Surface Wave Propagating Along the Interface Separating a Medium with a Step-wise Nonlinearity and a Gradient Medium with a Spatially Damping Refractive Index","authors":"S. E. Savotchenko","doi":"10.1007/s10773-026-06477-0","DOIUrl":"10.1007/s10773-026-06477-0","url":null,"abstract":"<div><p>New stationary TE wave propagating along the interface separating the medium with a step-wise nonlinear response and gradient medium with attenuation of the refractive index are described theoretically. The nonlinear problem is formulated and its exact analytical solution describing the wave is found. Effect of the optical parameters on the nonlinear surface wave beam width is described. The possibility to achieve the greatest localization of the field by exciting a surface wave with a laser beam at a critical angle of incidence is specified. The light intensity distribution can be controlled primarily by the angle of incidence of the beam exciting the nonlinear surface wave. Effect of the optical parameters on the total power flow and relative power flows in corresponding regions of the system considered is described. The largest share of the surface wave energy density is retained in the near-surface layer region. A comparative analysis of properties of the linear and nonlinear surface waves propagating along the gradient medium with the chosen refractive index profile is made. The difference between the spatial distribution intensity of the linear and nonlinear surface waves is described in details.</p></div>","PeriodicalId":597,"journal":{"name":"International Journal of Theoretical Physics","volume":"65 9","pages":""},"PeriodicalIF":2.3,"publicationDate":"2026-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148927580","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Conserved Vectors and Analytical Solutions of the (2+1)-Dimensional Modified Zakharov-Kuznetsov Model Arising in Electrical Engineering","authors":"Isaac Keoagile Mohapi,&nbsp;Letlhogonolo Daddy Moleleki,&nbsp;Mduduzi Yolane Thabo Lephoko,&nbsp;Karabo Plaatjie","doi":"10.1007/s10773-026-06462-7","DOIUrl":"10.1007/s10773-026-06462-7","url":null,"abstract":"<div><p>This paper examines the (2+1)-dimensional modified Zakharov-Kuznetsov equation, a nonlinear model arising in electrical engineering used to describe weakly nonlinear ion-acoustic waves in a plasma subjected to a uniform magnetic field. The model finds relevance in various domains such as nonlinear optics, plasma physics and fluid dynamics investigations. Thus, the main objective is to obtain novel analytical solutions by studying the model from a Lie group analysis standpoint, a methodological approach that has not been previously reported for this equation. An optimal system of one-dimensional subalgebras is constructed, from which similarity reductions and corresponding group-invariant solutions are derived. Several ansatz-based techniques are then employed to generate analytical solutions of the reduced equations. The analytical solutions are visualized through three-dimensional, two-dimensional, and density plots, demonstrating a variety of wave behaviours under appropriate choices of arbitrary constants and admissible parameter ranges. In addition, conserved vectors associated with the governing equation are derived using the multiplier method. These results will provide deeper insight into the structure and dynamics of the model and support further analytical and numerical studies. The validity of all the results presented in this study have been examined successfully through the use of the symbolic computation software Wolfram Mathematica.</p></div>","PeriodicalId":597,"journal":{"name":"International Journal of Theoretical Physics","volume":"65 9","pages":""},"PeriodicalIF":2.3,"publicationDate":"2026-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10773-026-06462-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148927099","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Thermodynamic and Dynamical Properties of Phantom Charged Black Holes in 4D Einstein–Gauss–Bonnet Gravity","authors":"B. Hamil","doi":"10.1007/s10773-026-06473-4","DOIUrl":"10.1007/s10773-026-06473-4","url":null,"abstract":"<div><p>We present charged black hole solutions of regularized four dimensional Einstein Gauss Bonnet gravity coupled to a phantom electromagnetic field. We investigate the combined effects of higher curvature corrections and phantom charge on the horizon structure, thermodynamics, geodesic motion, and scalar perturbations. The phantom sector exhibits properties that differ qualitatively from those of the ordinary Maxwell case, including the absence of critical thermodynamic behavior and persistent thermal instability. Circular geodesics and accretion efficiency are also significantly modified. Quasinormal modes are computed using the sixth-order WKB approximation and verified through time-domain evolution.</p></div>","PeriodicalId":597,"journal":{"name":"International Journal of Theoretical Physics","volume":"65 9","pages":""},"PeriodicalIF":2.3,"publicationDate":"2026-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148927098","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"State Transition of Quasi-Periodic Lump Chains to the Generalized Davey-Stewartson-Type System","authors":"Weiwei Luo,&nbsp;Zhaohua Li,&nbsp;Lihan Zhang,&nbsp;Zhonglong Zhao","doi":"10.1007/s10773-026-06480-5","DOIUrl":"10.1007/s10773-026-06480-5","url":null,"abstract":"<div><p>This paper extends the transformation mechanism of the lump chains to the quasi-periodic lump chains to study the transformed nonlinear waves of the generalized Davey-Stewartson-type system. With the aid of Hirota’s bilinear method, the one- and two-lump chain solutions can be obtained. Under special constraints, five types of transformed waves are generated. In addition, the quasi-periodic lump chains are constructed by means of the Riemann-theta function, which transforms the nonlinear over-determined systems into a solvable least squares problem. Five types of quasi-periodic transformed waves are obtained by applying transformation conditions to the quasi-periodic one-lump chains. Furthermore, for the quasi-periodic two-lump chains, semi-transformed collisions and full-transformed collisions are investigated. This study is crucial for predicting rogue waves in the marine environment and improving the warning capability for such catastrophic events.</p></div>","PeriodicalId":597,"journal":{"name":"International Journal of Theoretical Physics","volume":"65 9","pages":""},"PeriodicalIF":2.3,"publicationDate":"2026-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148927193","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Jacobi Elliptic Solutions of Fractional Phi-4, BBM, and KdV Equations: A Unified Framework","authors":"Gamze Kıratlı,&nbsp;Mutlu Akar","doi":"10.1007/s10773-026-06479-y","DOIUrl":"10.1007/s10773-026-06479-y","url":null,"abstract":"<div><p>This study develops a unified analytical framework for constructing exact travelling-wave solutions of the conformable time-fractional Phi-4, Benjamin–Bona–Mahony (BBM), and Korteweg–de Vries (KdV) equations. The three equations are treated simultaneously under the same travelling-wave transformation and auxiliary differential equation, enabling a direct comparative analysis of cubic nonlinearity in the Phi-4 equation against the quadratic nonlinear dispersive structures of the BBM and KdV equations (a comparison that single-equation studies cannot provide). By incorporating eleven Jacobi elliptic structures, including reciprocal forms (<span>(textrm{ns})</span>, <span>(textrm{nc})</span>, <span>(textrm{nd})</span>) and ratio-type forms (<span>(textrm{sc})</span>, <span>(textrm{sd})</span>, <span>(textrm{cs})</span>) in addition to the standard <span>(textrm{sn})</span>, <span>(textrm{cn})</span>, and <span>(textrm{dn})</span> functions, the framework produces wave profiles (periodic cnoidal waves, soliton-approaching pulses, asymmetric structures, and singular limiting forms) that standard approaches restricted to three elliptic functions cannot capture. The conformable fractional order is shown to act as a temporal scaling parameter that modifies the phase velocity of each wave type without altering its spatial structure, a behavior verified comparatively across all three models. Residual-based substitution confirms that the derived solutions satisfy the governing equations exactly. The obtained closed-form profiles are intended to serve as analytical reference solutions for future numerical, semi-analytical, and stability studies of fractional nonlinear dispersive wave equations.</p></div>","PeriodicalId":597,"journal":{"name":"International Journal of Theoretical Physics","volume":"65 9","pages":""},"PeriodicalIF":2.3,"publicationDate":"2026-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148927192","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Born–Oppenheimer Approximation From the (textsf{QU}) Decomposition of Bilinearly Coupled Harmonic Oscillators","authors":"Carlos A. Arango","doi":"10.1007/s10773-026-06476-1","DOIUrl":"10.1007/s10773-026-06476-1","url":null,"abstract":"<div><p>For two bilinearly coupled harmonic oscillators, whose exact solution is known analytically, the linear transformation from physical to normal-mode coordinates is obtained explicitly. This transformation belongs to <span>(textbf{GL}(textbf{2},mathbb {R}))</span> and admits a unique <span>(textsf{QU})</span> (Iwasawa) factorization into an orthogonal component describing symmetric mixing and an upper-triangular component encoding a hierarchical dependence of fast on slow coordinates. The Born–Oppenheimer approximation is identified with this triangular factor. In the adiabatic limit of small frequency ratio, the orthogonal contribution becomes negligible, and the exact transformation reduces to the Born–Oppenheimer map. This identification is supported by numerical comparisons of energies and wavefunctions across different coupling regimes.</p></div>","PeriodicalId":597,"journal":{"name":"International Journal of Theoretical Physics","volume":"65 9","pages":""},"PeriodicalIF":2.3,"publicationDate":"2026-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10773-026-06476-1.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148926728","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Liutex-based Identification and Quantum Analysis of Vortex Switching for the Lorenz-63 Model","authors":"Honglei Wu,&nbsp;Guilin Wen,&nbsp;Zihan Wang,&nbsp;Shuning Deng","doi":"10.1007/s10773-026-06459-2","DOIUrl":"10.1007/s10773-026-06459-2","url":null,"abstract":"<div><p>This study focuses on an innovative exploration for tracking the switching behavior in the classic Lorenz system (hereafter Lorenz-63 model) from the perspectives of fluid physics and quantum physics. As a model abstracted from a specific convection system and famous for chaotic behaviors, the Lorenz-63 model provides a theoretical prototype for the correlation between turbulence and the intrinsic chaos of nonlinear dynamics. Given the difficulty of identifying and predicting the states for high-dimensional chaotic systems, the Liutex method in turbulence research is creatively applied to capture the evolution of a flow in the strange attractor, which can be regarded as switching between vortices. Based on the Liutex method, the rules for identifying the switching can be established and the judgment of switching onset derived from the rules significantly precedes the observed occurrence of inter-vortex switching. Through comparison with the other two closest identification methods, this method has been verified to have advantages of lead time and accuracy. Statistics on switching points identified by this method also facilitate the estimation of the duration of vortices. A theoretical analysis for estimating the cycle number in distinct vortex regions is conducted within the framework of quantum mechanics; furthermore, by quantizing the chaotic system and drawing an analogy with the spin system, the particular solution for the two-level case is obtained. The form of this particular solution is also applicable to the <i>n</i>-level scenario, which provides a new paradigm for addressing the switching behavior in chaotic systems.</p></div>","PeriodicalId":597,"journal":{"name":"International Journal of Theoretical Physics","volume":"65 9","pages":""},"PeriodicalIF":2.3,"publicationDate":"2026-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148926776","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cosmological Implications of (f(T,L_{m})) Gravity Coupled with Modified Chaplygin Gas","authors":"Amit Samaddar,&nbsp;S. Surendra Singh","doi":"10.1007/s10773-026-06474-3","DOIUrl":"10.1007/s10773-026-06474-3","url":null,"abstract":"<div><p>The modified Chaplygin gas scenario is explored in the context of <span>(f(T,L_m))</span> gravity by employing the linear functional expression <span>(f(T,L_m)=delta T+beta L_m)</span>. From the conservation equation, we derive the corresponding form of the Hubble parameter and place constraints on the model parameters using the joint datasets of cosmic chronometers (CC), BAO observations and Type Ia supernova compilations (Pantheon+, DES-SN5Y and Union 3). The obtained value of the Hubble constant, <span>(H_0 approx 67text {-}68,mathrm {km, s^{-1}, Mpc^{-1}})</span>, is consistent with early-Universe determinations, while the MCG parameters satisfy all physical constraints and indicate a cosmology that nearly follows the <span>(Lambda )</span>CDM scenario with slight departures. Model selection diagnostics show that, although the proposed <span>(f(T,L_m))</span> model successfully reproduces the observed expansion history, the information criteria (<span>(Delta AICapprox 4)</span>, <span>(Delta BICapprox 15)</span>) favor the simpler <span>(Lambda )</span> CDM model because of its lower parameter complexity. Nevertheless, the proposed framework remains observationally viable and provides a consistent description of the late-time accelerated expansion of the Universe. A change from a decelerating expansion to an accelerating phase occurs at <span>(z_{tr} sim 0.57 text {-}0.60)</span>, as reflected by the deceleration parameter and supported by observations. The positivity of energy density together with negative pressure guarantees the occurrence of accelerated expansion. The EoS parameter begins in a matter-like state, later transitioning into a quintessence-dominated phase and asymptotically tending toward <span>(omega =-1)</span>. The satisfaction of energy conditions and the corresponding statefinder results provide additional evidence for the model’s physical reliability and its tendency toward the <span>(Lambda )</span>CDM limit. The model predicts a cosmic age of <span>(t_0 sim 13.3text {-}13.5)</span> Gyr, in agreement with observations, which confirms its robustness.</p></div>","PeriodicalId":597,"journal":{"name":"International Journal of Theoretical Physics","volume":"65 9","pages":""},"PeriodicalIF":2.3,"publicationDate":"2026-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148926717","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Metric Formulation of Free Particle Dynamics in Bohmian Mechanics","authors":"Felipe S. Escórcio,&nbsp;Hermano Velten","doi":"10.1007/s10773-026-06469-0","DOIUrl":"10.1007/s10773-026-06469-0","url":null,"abstract":"<div><p>In this work, we propose a geometric description of the quantum dynamics of a free particle based on phase perturbations. Using the hydrodynamic formalism and Bohmian quantum mechanics, and assuming a certain class of conditions/restrictions on the quantum potential, we derive an effective pseudo-Riemannian metric whose conformal factor is determined by the probability density, allowing the quantum dynamics to be reinterpreted in terms of the geodesic propagation of perturbations. This framework establishes a geometric structure that connects the causal propagation of such perturbations to the conditions under which they can influence Bohmian trajectories, providing a new perspective on the dynamical independence of different branches of the wave function and their possible interaction through the guiding equation. We apply this approach to a Gaussian wave packet, analyzing the resulting effective geometry and the associated causal horizon, as well as the conditions under which perturbations compatible with the adopted probability density cease to exert significant influence on the dynamics in question, so that the particle’s trajectory becomes effectively insensitive to additional fluctuations of the wave function.</p></div>","PeriodicalId":597,"journal":{"name":"International Journal of Theoretical Physics","volume":"65 9","pages":""},"PeriodicalIF":2.3,"publicationDate":"2026-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10773-026-06469-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148926546","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Analysis on the Internal Structure of Shock-front in a Self-gravitating Gas","authors":"Anmol Singh,&nbsp;Raj Kumar Anand","doi":"10.1007/s10773-026-06466-3","DOIUrl":"10.1007/s10773-026-06466-3","url":null,"abstract":"<div><p>In the present analysis, we investigate the effect of self-gravitating parameters on the internal structure of a shock-front in a self-gravitating gaseous medium. Using continuum hydrodynamics model, the exact solution and analytical expression of the different flow variables are obtained, and thereafter, the width of the shock front is calculated. In addition, the variation in the thickness due to various parameters, namely the shock strength <i>M</i>, the density parameter <i>w</i>, and the gravitational parameter <i>D</i>, is analysed within the shock transition region. The asymptotic variations in the thickness of the shock-front due to these flow parameters have been discussed and analysed numerically and graphically. The findings confirm that the shock-front thickness is significantly affected not only by various physical parameters but also by the properties of the gaseous medium across the shock-front. The present outcomes show that gravitational parameters should be included for more reliable predictions about the nature of shock wave fronts in various geophysical and astrophysical atmospheres.</p></div>","PeriodicalId":597,"journal":{"name":"International Journal of Theoretical Physics","volume":"65 9","pages":""},"PeriodicalIF":2.3,"publicationDate":"2026-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148926197","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}