This article analyzes the greybody factor for a charged black hole coupled with the improved quantum gravity. Assuming a minimal coupling between the black hole geometry and a massless scalar field, we employ the Klein–Gordon equation to derive the corresponding radial wave equation. The introduction of the tortoise coordinate allows the radial equation to be recast into a Schrödinger-like form, allowing the identification of an effective potential barrier governing the propagation of Hawking radiation. The graphical analysis of this potential is also carried out by varying all relevant parameters appearing in the spacetime metric, providing insight into the filtering effect of the geometry on outgoing radiation. Finally, we use an analytical matching technique to find exact solutions of the radial equation in both the outer and far-away regions. Both solutions are then matched in the middle regime to obtain the greybody factor, which is further studied graphically. It is observed that the modified parameter reduces the greybody factor at higher frequency modes, and thus the black hole does not evaporate. Notably, the charge parameter increases and the mass reduces the evaporation process.
This study is about managing solitons inside waveguides. The waveguides have a structure that follows a dual-power law, which determines how light travels through them. Optical solitons are very important for creating fiber networks. To make these networks work properly, we need to control the solitons very precisely. Other people have done research on solitons before. They have tried to figure out how to change things like the strength of the optical solitons and how wide the optical solitons are. However, the important aspect of controlling the speed of optical solitons, which is crucial for timing and routing in optical communication systems, has not been adequately addressed. This gap is particularly significant because velocity control enables precise pulse scheduling and synchronization in fiber-optic networks. Nobody has really thought about how to control the speed of solitons. We need to pay attention to controlling the speed of optical solitons. To fix this problem, we made a model based on the nonlinear Schrödinger equation. This model includes dispersion that changes over time and two kinds of parts that follow power laws. Our model lets us change the speed of solitons easily, even when the waves are moving through uneven paths, like in irregular waveguide settings, and this is all about controlling the speed of optical solitons. Given the model’s strongly nonlinear nature and the limitations of existing methods that typically handle only specific cases (e.g., Kerr nonlinearity with p=2 and R2(t)=0) we employed two powerful analytical approaches, the Kudryashov technique and the newly developed (G′kG′+G+r)-expansion method, to derive precise, reliable, and rigorously validated solutions. These methods were specifically chosen for their complementary strengths: the Kudryashov method provides simplicity and systematic procedures, while the expansion method offers flexibility in generating multiple families of solutions (hyperbolic, trigonometric) from a unified framework. The novelty of this work lies in three key aspects: (i) it addresses the unexplored problem of active soliton velocity control in inhomogeneous waveguides with dual-power-law nonlinearity for arbitrary exponent p, extending beyond the Kerr case (p=2) studied previously; (ii) it provides explicit closed-form formulas for velocity engineering through temporal modulation of the dispersion coefficient; and (iii) it establishes a unified analytical framework combining Kudryashov and (G′kG′+G+r)-expansion methods that systematically handles higher-order nonlinearities.
This paper aims to focus on pilgrim dark energy in f(R,T2) gravity, where R refers to Ricci scalars and T2=TμνTμν is the self-contraction of stress energy tensor. We will use particle horizon, event horizon and conformal age of the universe as infrared cut-offs in understanding the cosmological evolution. We explore the behavior of various cosmological parameters with respect to different infrared cut-offs in this theoretical framework. We apply squared sound speed method to check the stability of all the horizons. It reveals that the pilgrim dark energy model has indeed been able to support the accelerated expansion of the universe. To further analyze its behavior, standard diagnostic tools such as the ωPDE−ωPDE′ analysis and the statefinder parameters (r,s) have been employed. We have gained new insights into the interplay between dark energy models and modified gravitational theories, enhancing our understanding of cosmic evolution.
This dissertation presents a comprehensive investigation of the (3+1)-dimensional Zakharov-Kuznetsov-Burgers model to examine shock wave structure in dusty plasmas with quantum effects. The presented model provides significant physical insight into nonlinear dissipative and dispersive phenomenons that naturally emerge in charged dust-ion environments, making it relevant for both astrophysical plasmas and laboratory experiments. In addition, the framework extends to hydrodynamical systems, where dispersion and dissipation govern nonlinear wave interactions. To obtain exact analytical solutions, we utilize the Riccati sub-equation method and the generalized Arnous method. Various nonlinear structures are determined, including kink waves, dark solitons, dark-bright excitations, combined soliton states, and singular solitons. These diverse solutions not only represent the mathematical richness of the Zakharov-Kuznetsov-Burgers model but also emphasize its applicability in modeling nonlinear dynamical behavior in both fluid hydrodynamics and plasma physics.
This study investigates cosmological dynamics within the framework of Finsler geometry utilizing the Barthel connection and osculating Riemannian techniques in Randers spaces. Anisotropy is introduced via the parameter 7(t) which arises from an intrinsic vector field. The Hubble parameter is derived and model parameters are constrained using Markov Chain Monte Carlo techniques applied to Cosmic Chronometer, Baryon Acoustic Oscillation , and Pantheon+ SH0ES datasets. The results indicate that the model effectively captures the accelerating expansion of the universe with a deceleration parameter q(z) approximate to -0.19 and an equation of state parameter a approximate to-0.6 highlighting the role of dark energy. The jerk and snap parameters are analyzed providing further insights into the late-time acceleration of the universe showcasing the model capacity to describe anisotropic corrections. Additionally the information criterion is used to compare the Finslerian model with the standard ACDM framework demonstrating a better fit to the data. This study emphasizes the importance of Finslerian geometry in refining our understanding of cosmological expansion and offers a more comprehensive view of the universe evolution.
In this study, we investigated the effects of pusher layer density and mass on fuel density, areal density, implosion velocity, and fuel ion temperature in an implosion process for a multilayered-structure target pellet in heavy-ion inertial fusion with a direct-indirect mixture mode. A dense material outside the fuel layer was proposed to suppress preheating due to radiation transport in the radial direction for implosion robustness. In this study, we investigated aluminum (Al) as a lower-density material and lead (Pb) as a higher-density material for the pusher layer placed outside the fuel layer. The implosion process was modeled as 1D spherical coordinate radiative hydrodynamics, with a numerical calculation code developed for the Lagrangian system. The compression ratio and areal density of the Pb pusher are higher than those of the Al pusher, while the implosion velocity of the Al pusher exceeds that of the Pb pusher. Although the implosion velocity of the Pb pusher was lower for the same pusher mass, the implosion parameters obtained were higher for the Pb pusher. The fuel isentrope parameter was successfully maintained at a small value in the Pb pusher. Moreover, the increase in fuel isentrope parameter caused by the increased pusher mass was insignificant. The results suggest that the pusher density and mass are critical parameters for obtaining sufficient fusion output.
Terahertz (THz) radiation can be produced by plasma, which is a promising method in both plasma physics and optics. In this approach, high-power laser (likes Nd-glass) is used to excite the plasma and generate electromagnetic waves in the THz range. A common mechanism involves irradiating the plasma with two lasers whose frequencies are close to each other. Through interference, a THz-frequency wave emerges due to nonlinear plasma effects, leading to THz radiation. Key parameters—such as laser intensity, plasma species, density, temperature, and magnetic field—significantly influence the process. Some methods require specific conditions for temperature, density, and magnetic field to optimize THz generation. The ability to use plasma as a medium for THz production has important implications for research in plasma physics, laser-plasma interactions, and THz applications. Our analysis indicates that an external magnetic field can enhance the THz radiation yield.
Sulfur nanoparticle (NPs) solutions were prepared by using the laser ablation of sulfur targets in distilled water. A ns pulsed Nd:YAG laser operated at an energy of 300 mJ, with a wavelength of 1064 nm and a repetition rate of 1 Hz. The concentration of nanoparticles was controlled by the measured ablation yield (1 & micro;g/pulse at 300 mJ) and the total irradiation time, which ranged from 30 min to 3 h. The NPs solution was characterized using various optical spectroscopic techniques in the visible, near-UV, and IR regions. Crystalline NPs were synthesized with a spherical shape and a size of about 20 nm. Additionally, several physical parameters of the NPs solution were measured, including density, surface tension, viscosity, pH, and wetting angle on different surfaces. The laser-generated sulfur-plasma was investigated in a vacuum to enhance understanding of its atomic and molecular composition. A mass quadrupole spectrometer was employed to observe the S molecules generated by atom nucleation in a vacuum. Some applications of sulfur nanoparticles are presented and discussed.
We present an investigation of isotropic compact stars within the framework of Ricci inverse gravity extended by a trace term T, which introduces a direct matter-geometry coupling. Employing the Krori-Barua metric potentials to describe the interior spacetime, the model parameters are constrained through smooth matching with the Schwarzschild exterior solution and the use of observational data from well-known stellar candidates. The physical behavior of the resulting configurations is analyzed in detail, encompassing matter density, isotropic pressure profiles, equation of state parameter, causality condition, and energy bounds. Stability is further assessed through the modified Tolman-Oppenheimer-Volkoff equation and sound speed criteria, ensuring a consistent and equilibrium-preserving structure. Also, global properties such as the mass-radius relation, compactness, and surface redshift are explored to assess astrophysical viability. The results demonstrate that the proposed isotropic configurations satisfy all fundamental physical requirements, thereby establishing Ricci inverse gravity with a trace term T as a viable framework for describing the internal dynamics of dense stellar objects beyond the scope of General Relativity.
We present a distorted-wave with exchange (DWE) formulation for computing electron-impact ionization (EII) cross sections within the recently developed excited states method (ESM) for plasmas. The ESM provides a self-consistent quantum-mechanical description of both bound and continuum electronic states in dense plasmas, incorporating finite-temperature and screening effects absent in isolated-atom approaches. Using this framework, we calculate EII cross sections for lithium across a wide range of temperatures and densities. We show that the ESM reproduces the isolated-atom limit at low densities while capturing strong plasma effects, such as pressure ionization and shape resonances, at solid density. Comparisons with isolated-atom DWE and average-atom (AA) calculations reveal that, although AA cross sections can approximate configuration average behavior, the ESM provides more accurate, state-resolved answers. These results demonstrate that the ESM allows one to obtain rate coefficients for collisional-radiative modeling of plasmas out of local thermodynamical equilibrium.
In this paper, we examine the effects of f(Q) gravity on the anisotropic pulsar star SAX J1748.9-2021, with Q representing non-metricity. The internal structure of the system is modeled using the Krori-Barua metric under anisotropic fluid conditions, employing the quadratic model of f(Q) gravity. Astrophysical observations from the pulsar SAX J1748.9-2021, collected from X-ray binary bursts in globular clusters, are used to investigate various geometric and physical properties. We explore the behavior of some physical characteristics like matter variables, anisotropy, mass-radius relation, redshift, the Zeldovich condition, energy conditions, causality conditions, adiabatic index, Tolman-Oppenheimer-Volkoff equation, equation of state parameter and compactness. It is found that these quantities show consistency with other observational data. This study supports the viability and stability of the pulsar SAX J1748.92021 in the framework of the modified gravity theory.
This manuscript studies the viability and stability of charged neutron stars exhibiting anisotropic matter distribution within the framework of f(Q,Lm) gravity (Q denotes non-metricity and Lm represents the matter Lagrangian). A specific functional form of this theory is adopted to derive explicit expressions for the field equations, which describe the interplay between matter and geometry. The structure of static spherically symmetric system is analyzed using two novel non-singular solutions. The unknown constants in the metric potentials are determined by employing smooth matching conditions at the stellar boundary. A graphical analysis of key physical properties is conducted to asses the viable neutron stars. Furthermore, the stability of these charged stellar objects is examined through different methods. We conclude that these charged stellar configurations are both viable and stable, as they satisfy all necessary physical conditions.
In this work, we explore the construction and physical viability of Casimir wormholes within the context of modified gravity defined by f (R, Lm, T) = R + x1Lm + x2T, where x1 and x2 denote the coupling constants associated with the matter Lagrangian and the trace of the energy-momentum tensor, respectively. We explore two scenarios: one without and one with the inclusion of quantum gravity effects through the Generalized Uncertainty Principle (GUP), considering both KMM and DGS models. Without incorporating GUP corrections, we obtain exact shape functions sustained by Casimir energy and demonstrate that essential wormhole criteria-like the flaring-out condition and asymptotic flatness-are met, though some energy conditions are violated in the vicinity of the throat. Including GUP corrections improves the physical plausibility of the solutions by confining the exotic matter to a smaller region and reducing the extent of energy condition violations. We examine the pressure anisotropy, evaluate the energy conditions and utilize the volume integral quantifier to assess the amount of exotic matter present. The TOV equation analysis confirms mechanical stability, achieved through a balance of hydrostatic and anisotropic forces. Our findings confirm that Casimir wormholes are feasible within this extended gravity framework, and that GUP corrections significantly contribute to enhance their physical viability.
Our investigation develops two new singularity-free interior solutions, describing spherical anisotropic configurations within the framework of f(R,T) gravity. The modified Einstein field equations are established along with the expression of anisotropic pressure for a static geometry. Two independent constraints are imposed to solve the resulting field equations. In each case, we solve differential equations for temporal metric function under the assumption of radial potential and the anisotropic factor. Such an integration results in multiple integration constants that are fixed by matching the interior line element with the Schwarzschild exterior solution at the stellar surface. The vanishing radial condition at the surface also serves as an additional constraint. Afterwards, we investigate particular requirements whose fulfillment produce physically feasible compact star models. For graphical evaluation, we utilize observational data from two compact objects, namely SMC X-4 and 4U 1820-30, and vary the model parameter. Our analysis demonstrates that both stellar models satisfy all necessary physical acceptability conditions for specific parametric choices.
The Friedmann-Robertson-Walker (FRW) cosmological model is analysed within the framework of f(R,G,T) gravity, where T denotes the trace of the energy-momentum tensor, G is the Gauss-Bonnet invariant, and R is the Ricci scalar. We consider the functional form f (R, G, T) = R+ R2 + 2 G (-T)m, where 2 and m are model parameters. Adopting a newly proposed deceleration parameter, q(z) = q0 + az+b(z2+z3)1+z2 , we employ the Markov Chain Monte Carlo (MCMC) method to find the constrained values of the cosmological parameters using Hubble, BAO, and Pantheon+ datasets. Our analysis shows that the pressure becomes negative for z--1 after z approximate to 0.42, while the energy density remains positive for all z. The deceleration parameter converges to-1, with a present value q0 = -0.54 which implies that the present stage of accelerated expansion. The equation-of-state parameter ! also approaches to-1 at late times which is consistent with a dark energy dominated era. Examination of the energy conditions reveals that the Strong Energy Condition (SEC) fails for z--1 supporting the interpretation of ongoing late-time cosmic acceleration. State finder diagnostics indicate a transition from a Quintessence regime to a ACDM-like behaviour which is in agreement with current observational data. Furthermore, the total entropy of the Universe increases monotonically as z--1, thereby satisfying the second law of thermodynamics. The positivity of the squared sound speed throughout the evolution further ensures the absence of gradient instabilities, confirming the perturbative stability of the proposed f(R,G,T) cosmological model.
The amplification of ultrashort laser pulses has attracted significant attention in recent years. An advanced approach involves utilizing plasma as a medium for the amplification process. In this research, we conduct particle-in-cell (PIC) simulations to study the interaction between two counter-propagating seed and pump pulses in a plasma with sub-quarter-critical density. To reduce noise in the simulations, we initially optimized the number of particles per cell. Various plasma conditions affecting the amplification process are considered. The findings reveal that among the studied cases, density ramps and plasma lengths significantly influence energy transfer efficiency. The seed pulse reaches maximum amplification at a plasma density of 0.0104 ner, where the largest Brillouin peak is observed. For the three ramp shapes-linear, quadratic, and exponential-the results show that quadratic ramps achieve the highest amplification levels due to the enhanced phase matching condition. It was also found that seed amplification is more effective with asymmetric density ramps. These insights contribute to the optimization of plasma-based stimulated Brillouin scattering for achieving ultrahigh-intensity laser pulses in applications ranging from inertial confinement fusion to high-energy particle acceleration.
In this article, the Korteweg-de Vries-Burgers equation (KdVBE) is derived for ion-acoustic shocks in a dusty plasma considering warm ions, electrons and dust. The set of equations is normalized using different schemes, and the reductive perturbation technique (RPT) is applied to derive the model. The KdVBE is converted to time fractional KdVBE and then numerical scheme is formulated for the solution of time fractional KdVBE. A radial basis function collocation scheme and the Crank-Nicolson scheme are applied on time fractional KdVBE. The time-fractional derivative is discretized using the Caputo-Fabrizio fractional derivative. Moreover, a theta-weighted scheme is implemented for the spatial derivatives, in which radial basis functions are used for space derivatives in which radial basis function is used to approximate the derivatives. The behaviour of the method is assessed with the help of graphs and tables, and also shows the effect of the Caputo-Fabrizio fractional derivative. Numerical simulations indicate that the proposed scheme is highly efficient to find more accurate results. The solution is obtained for a variety of parameters to describe their behaviour of parameters like temperature ratio, fractional parameter and non-extensive distribution. The accuracy of the proposed method is verified by comparing the results with other methods in the literature.
