Pub Date : 2024-09-12DOI: 10.1088/1572-9494/ad6b1c
Yilin Wang and Biao Li
We construct the Riemann–Hilbert problem of the Lakshmanan–Porsezian–Daniel equation with nonzero boundary conditions, and use the Laurent expansion and Taylor series expansion to obtain the exact formulas of the soliton solutions in the case of a higher-order pole and multiple higher-order poles. The dynamic behaviors of a simple pole, a second-order pole and a simple pole plus a second-order pole are demonstrated.
{"title":"Riemann–Hilbert approach and soliton solutions for the Lakshmanan–Porsezian–Daniel equation with nonzero boundary conditions","authors":"Yilin Wang and Biao Li","doi":"10.1088/1572-9494/ad6b1c","DOIUrl":"https://doi.org/10.1088/1572-9494/ad6b1c","url":null,"abstract":"We construct the Riemann–Hilbert problem of the Lakshmanan–Porsezian–Daniel equation with nonzero boundary conditions, and use the Laurent expansion and Taylor series expansion to obtain the exact formulas of the soliton solutions in the case of a higher-order pole and multiple higher-order poles. The dynamic behaviors of a simple pole, a second-order pole and a simple pole plus a second-order pole are demonstrated.","PeriodicalId":10641,"journal":{"name":"Communications in Theoretical Physics","volume":"394 1","pages":""},"PeriodicalIF":3.1,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190305","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
Pub Date : 2024-09-09DOI: 10.1088/1572-9494/ad597d
WenShan Xu, Ri-Gui Zhou, YaoChong Li and XiaoXue Zhang
Variational quantum algorithms are promising methods with the greatest potential to achieve quantum advantage, widely employed in the era of noisy intermediate-scale quantum computing. This study presents an advanced variational hybrid algorithm (EVQLSE) that leverages both quantum and classical computing paradigms to address the solution of linear equation systems. Initially, an innovative loss function is proposed, drawing inspiration from the similarity measure between two quantum states. This function exhibits a substantial improvement in computational complexity when benchmarked against the variational quantum linear solver. Subsequently, a specialized parameterized quantum circuit structure is presented for small-scale linear systems, which exhibits powerful expressive capabilities. Through rigorous numerical analysis, the expressiveness of this circuit structure is quantitatively assessed using a variational quantum regression algorithm, and it obtained the best score compared to the others. Moreover, the expansion in system size is accompanied by an increase in the number of parameters, placing considerable strain on the training process for the algorithm. To address this challenge, an optimization strategy known as quantum parameter sharing is introduced, which proficiently minimizes parameter volume while adhering to exacting precision standards. Finally, EVQLSE is successfully implemented on a quantum computing platform provided by IBM for the resolution of large-scale problems characterized by a dimensionality of 220.
变分量子算法是最有潜力实现量子优势的方法，在噪声中等规模量子计算时代得到广泛应用。本研究提出了一种先进的变分混合算法（EVQLSE），利用量子和经典计算范式来解决线性方程组的求解问题。首先，从两个量子态之间的相似性度量中汲取灵感，提出了一种创新的损失函数。与变分量子线性求解器相比，该函数的计算复杂度有了大幅提高。随后，针对小规模线性系统提出了一种专门的参数化量子电路结构，该结构具有强大的表达能力。通过严格的数值分析，利用变分量子回归算法对该电路结构的表达能力进行了定量评估，结果表明，与其他电路结构相比，该电路结构的得分最高。此外，系统规模的扩大伴随着参数数量的增加，给算法的训练过程带来了相当大的压力。为了应对这一挑战，我们引入了一种称为量子参数共享的优化策略，在严格遵守精度标准的同时，有效地减少了参数数量。最后，EVQLSE 在 IBM 提供的量子计算平台上成功实现，用于解决维度为 220 的大规模问题。
{"title":"Towards an efficient variational quantum algorithm for solving linear equations","authors":"WenShan Xu, Ri-Gui Zhou, YaoChong Li and XiaoXue Zhang","doi":"10.1088/1572-9494/ad597d","DOIUrl":"https://doi.org/10.1088/1572-9494/ad597d","url":null,"abstract":"Variational quantum algorithms are promising methods with the greatest potential to achieve quantum advantage, widely employed in the era of noisy intermediate-scale quantum computing. This study presents an advanced variational hybrid algorithm (EVQLSE) that leverages both quantum and classical computing paradigms to address the solution of linear equation systems. Initially, an innovative loss function is proposed, drawing inspiration from the similarity measure between two quantum states. This function exhibits a substantial improvement in computational complexity when benchmarked against the variational quantum linear solver. Subsequently, a specialized parameterized quantum circuit structure is presented for small-scale linear systems, which exhibits powerful expressive capabilities. Through rigorous numerical analysis, the expressiveness of this circuit structure is quantitatively assessed using a variational quantum regression algorithm, and it obtained the best score compared to the others. Moreover, the expansion in system size is accompanied by an increase in the number of parameters, placing considerable strain on the training process for the algorithm. To address this challenge, an optimization strategy known as quantum parameter sharing is introduced, which proficiently minimizes parameter volume while adhering to exacting precision standards. Finally, EVQLSE is successfully implemented on a quantum computing platform provided by IBM for the resolution of large-scale problems characterized by a dimensionality of 220.","PeriodicalId":10641,"journal":{"name":"Communications in Theoretical Physics","volume":"35 1","pages":""},"PeriodicalIF":3.1,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190306","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
Pub Date : 2024-09-04DOI: 10.1088/1572-9494/ad6a04
XiaoXia Yang, Lingling Xue, Q P Liu
In this paper, we study the N = 2 a = 1 supersymmetric KdV equation. We construct its Darboux transformation and the associated Bäcklund transformation. Furthermore, we derive a nonlinear superposition formula, and as applications we calculate some solutions for this supersymmetric KdV equation and recover the related results for the Kersten–Krasil’shchik coupled KdV-mKdV system.
本文研究 N = 2 a = 1 超对称 KdV 方程。我们构建了它的达布变换和相关的贝克伦德变换。此外，我们还推导了一个非线性叠加公式，作为应用，我们计算了这个超对称KdV方程的一些解，并恢复了Kersten-Krasil'shchik耦合KdV-mKdV系统的相关结果。
{"title":"N = 2 a = 1 supersymmetric KdV equation and its Darboux–Bäcklund transformations","authors":"XiaoXia Yang, Lingling Xue, Q P Liu","doi":"10.1088/1572-9494/ad6a04","DOIUrl":"https://doi.org/10.1088/1572-9494/ad6a04","url":null,"abstract":"In this paper, we study the <italic toggle=\"yes\">N</italic> = 2 <italic toggle=\"yes\">a</italic> = 1 supersymmetric KdV equation. We construct its Darboux transformation and the associated Bäcklund transformation. Furthermore, we derive a nonlinear superposition formula, and as applications we calculate some solutions for this supersymmetric KdV equation and recover the related results for the Kersten–Krasil’shchik coupled KdV-mKdV system.","PeriodicalId":10641,"journal":{"name":"Communications in Theoretical Physics","volume":"29 1","pages":""},"PeriodicalIF":3.1,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190356","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
Pub Date : 2024-09-04DOI: 10.1088/1572-9494/ad696b
Ruofan Chen
Most path integral expressions for quantum open systems are formulated with diagonal system-bath coupling, where the influence functional is a functional of scalar-valued trajectories. This formalism is enough if only a single bath is under consideration. However, when multiple baths are present, non-diagonal system-bath couplings need to be taken into consideration. In such a situation, using an abstract Liouvillian method, the influence functional can be obtained as a functional of operator-valued trajectories. The value of the influence functional itself also becomes a superoperator rather than an ordinary scalar, whose meaning is ambiguous at first glance and its connection to the conventional understanding of the influence functional needs extra careful consideration. In this article, we present another concrete derivation of the superoperator-valued influence functional based on the straightforward Trotter–Suzuki splitting, which can provide a clear picture to interpret the superoperator-valued influence functional.
{"title":"Path integral formalism of open quantum systems with non-diagonal system-bath coupling","authors":"Ruofan Chen","doi":"10.1088/1572-9494/ad696b","DOIUrl":"https://doi.org/10.1088/1572-9494/ad696b","url":null,"abstract":"Most path integral expressions for quantum open systems are formulated with diagonal system-bath coupling, where the influence functional is a functional of scalar-valued trajectories. This formalism is enough if only a single bath is under consideration. However, when multiple baths are present, non-diagonal system-bath couplings need to be taken into consideration. In such a situation, using an abstract Liouvillian method, the influence functional can be obtained as a functional of operator-valued trajectories. The value of the influence functional itself also becomes a superoperator rather than an ordinary scalar, whose meaning is ambiguous at first glance and its connection to the conventional understanding of the influence functional needs extra careful consideration. In this article, we present another concrete derivation of the superoperator-valued influence functional based on the straightforward Trotter–Suzuki splitting, which can provide a clear picture to interpret the superoperator-valued influence functional.","PeriodicalId":10641,"journal":{"name":"Communications in Theoretical Physics","volume":"14 1","pages":""},"PeriodicalIF":3.1,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190307","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
Pub Date : 2024-09-03DOI: 10.1088/1572-9494/ad6852
Xi Huang, Yingting Yi, Qianju Song, Zao Yi, Can Ma, Chaojun Tang, Qingdong Zeng, Shubo Cheng, Rizwan Raza
Solar energy has always been a kind of energy with large reserves and wide application. It is well utilized through solar absorbers. In our study, the finite difference time domain method (FDTD) is used to simulate the absorber composed of refractory metal materials, and its absorption performance and thermal emission performance are obtained. The ultra-wide band of 200 nm–3000 nm reaches 95.93% absorption efficiency, of which the bandwidth absorption efficiency of 2533 nm (200 nm–2733 nm) is greater than 90%. The absorption efficiency in the whole spectrum range (200 nm–2733 nm) is 97.17% on average. The multilayer nanodisk structure of the absorber allows it to undergo strong surface plasmon resonance and near-field coupling when irradiated by incident light. The thermal emission performance of the absorber enables it to also be applied to the thermal emitter. The thermal emission efficiency of 95.37% can be achieved at a high temperature of up to 1500 K. Moreover, the changes of polarization and incident angle do not cause significant changes in absorption. Under the gradual change of polarization angle (0°–90°), the absorption spectrum maintains a high degree of consistency. As the incident angle increases from 0° to 60°, there is still 85% absorption efficiency. The high absorption efficiency and excellent thermal radiation intensity of ultra-wideband enable it to be deeply used in energy absorption and conversion applications.
{"title":"Simulation study of multi-layer titanium nitride nanodisk broadband solar absorber and thermal emitter","authors":"Xi Huang, Yingting Yi, Qianju Song, Zao Yi, Can Ma, Chaojun Tang, Qingdong Zeng, Shubo Cheng, Rizwan Raza","doi":"10.1088/1572-9494/ad6852","DOIUrl":"https://doi.org/10.1088/1572-9494/ad6852","url":null,"abstract":"Solar energy has always been a kind of energy with large reserves and wide application. It is well utilized through solar absorbers. In our study, the finite difference time domain method (FDTD) is used to simulate the absorber composed of refractory metal materials, and its absorption performance and thermal emission performance are obtained. The ultra-wide band of 200 nm–3000 nm reaches 95.93% absorption efficiency, of which the bandwidth absorption efficiency of 2533 nm (200 nm–2733 nm) is greater than 90%. The absorption efficiency in the whole spectrum range (200 nm–2733 nm) is 97.17% on average. The multilayer nanodisk structure of the absorber allows it to undergo strong surface plasmon resonance and near-field coupling when irradiated by incident light. The thermal emission performance of the absorber enables it to also be applied to the thermal emitter. The thermal emission efficiency of 95.37% can be achieved at a high temperature of up to 1500 K. Moreover, the changes of polarization and incident angle do not cause significant changes in absorption. Under the gradual change of polarization angle (0°–90°), the absorption spectrum maintains a high degree of consistency. As the incident angle increases from 0° to 60°, there is still 85% absorption efficiency. The high absorption efficiency and excellent thermal radiation intensity of ultra-wideband enable it to be deeply used in energy absorption and conversion applications.","PeriodicalId":10641,"journal":{"name":"Communications in Theoretical Physics","volume":"1 1","pages":""},"PeriodicalIF":3.1,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190309","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
Pub Date : 2024-08-21DOI: 10.1088/1572-9494/ad5aeb
Peixiang Ji, Lijing Shao
The reason for the present accelerated expansion of the Universe stands as one of the most profound questions in the realm of science, with deep connections to both cosmology and fundamental physics. From a cosmological point of view, physical models aimed at elucidating the observed expansion can be categorized into two major classes: dark energy and modified gravity. We review various major approaches that employ a single scalar field to account for the accelerating phase of our present Universe. Dynamic system analysis was employed in several important models to find cosmological solutions that exhibit an accelerating phase as an attractor. For scalar field models of dark energy, we consistently focused on addressing challenges related to the fine-tuning and coincidence problems in cosmology, as well as exploring potential solutions to them. For scalar–tensor theories and their generalizations, we emphasize the importance of constraints on theoretical parameters to ensure overall consistency with experimental tests. Models or theories that could potentially explain the Hubble tension are also emphasized throughout this review.
{"title":"Scalar dark energy models and scalar–tensor gravity: theoretical explanations for the accelerated expansion of the present Universe","authors":"Peixiang Ji, Lijing Shao","doi":"10.1088/1572-9494/ad5aeb","DOIUrl":"https://doi.org/10.1088/1572-9494/ad5aeb","url":null,"abstract":"The reason for the present accelerated expansion of the Universe stands as one of the most profound questions in the realm of science, with deep connections to both cosmology and fundamental physics. From a cosmological point of view, physical models aimed at elucidating the observed expansion can be categorized into two major classes: dark energy and modified gravity. We review various major approaches that employ a single scalar field to account for the accelerating phase of our present Universe. Dynamic system analysis was employed in several important models to find cosmological solutions that exhibit an accelerating phase as an attractor. For scalar field models of dark energy, we consistently focused on addressing challenges related to the fine-tuning and coincidence problems in cosmology, as well as exploring potential solutions to them. For scalar–tensor theories and their generalizations, we emphasize the importance of constraints on theoretical parameters to ensure overall consistency with experimental tests. Models or theories that could potentially explain the Hubble tension are also emphasized throughout this review.","PeriodicalId":10641,"journal":{"name":"Communications in Theoretical Physics","volume":"68 1","pages":""},"PeriodicalIF":3.1,"publicationDate":"2024-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190358","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
Pub Date : 2024-08-21DOI: 10.1088/1572-9494/ad6853
Ziyodulla Turakhonov, Farruh Atamurotov, Ali Övgün, Ahmadjon Abdujabbarov, Sunnatillo Urinov
In this study, we examine the effects of weak gravitational lensing and determine the shadow radius around black holes within the Dyonic ModMax (DM) spacetime, also accounting for models with nonuniform plasma distributions. By analyzing various gravitational lens models, we compare corrections to vacuum lensing due to gravitational effects within plasma and plasma inhomogeneity, finding that these effects could be observed in hot gas within galaxy clusters. Starting with the orbits of photons around a black hole in DM, we investigate the shadow and weak gravitational lensing phenomena. Utilizing observational data from the Event Horizon Telescope for M87* and SgrA*, we constrain parameters within DM gravity. To connect our findings to observations, we examine the magnification and positioning of lensed images, along with the weak deflection angle and magnification for sources near different galaxies.
{"title":"Weak gravitational lensing around dyonic ModMax black hole in plasma","authors":"Ziyodulla Turakhonov, Farruh Atamurotov, Ali Övgün, Ahmadjon Abdujabbarov, Sunnatillo Urinov","doi":"10.1088/1572-9494/ad6853","DOIUrl":"https://doi.org/10.1088/1572-9494/ad6853","url":null,"abstract":"In this study, we examine the effects of weak gravitational lensing and determine the shadow radius around black holes within the Dyonic ModMax (DM) spacetime, also accounting for models with nonuniform plasma distributions. By analyzing various gravitational lens models, we compare corrections to vacuum lensing due to gravitational effects within plasma and plasma inhomogeneity, finding that these effects could be observed in hot gas within galaxy clusters. Starting with the orbits of photons around a black hole in DM, we investigate the shadow and weak gravitational lensing phenomena. Utilizing observational data from the Event Horizon Telescope for M87* and SgrA*, we constrain parameters within DM gravity. To connect our findings to observations, we examine the magnification and positioning of lensed images, along with the weak deflection angle and magnification for sources near different galaxies.","PeriodicalId":10641,"journal":{"name":"Communications in Theoretical Physics","volume":"9 1","pages":""},"PeriodicalIF":3.1,"publicationDate":"2024-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142224758","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
Pub Date : 2024-08-21DOI: 10.1088/1572-9494/ad595d
Xi-Kui Hu, Song Zhu, Juan Yang, Zhao Yao, Ping Zhou, Jun Ma
A gas sensor can convert external gas concentration or species into electric voltage or current signals by physical adsorption or chemical changes. As a result, a gas sensor in a nonlinear circuit can be used as a sensitive sensor for detecting external gas signals from the olfactory system. In this paper, a gas sensor and a field-effect transistor are incorporated into a simple FithzHugh–Nagumo neural circuit for capturing and encoding external gas signals. An improved functional neural circuit is obtained, and the effect of gas concentration, gas species and neuronal activity can be discerned as the gate voltage, threshold voltage and activation coefficient of the field-effect transistor, respectively. The gas concentration can affect the neural activities from quiescent to normal working and, finally, to saturation state in bursting, spiking, periodic and chaotic firings with different frequencies. The effects of gas species and neuronal activity on the firing state can also be achieved in this functional neural circuit. In addition, variations in the gate voltage, threshold voltage and activation coefficient can cause switching between different firing modes. These results can be helpful in designing artificial olfactory devices for bionic gas recognition and other coupled systems arising in applied sciences.
{"title":"A gas sensing neural circuit for an olfactory neuron","authors":"Xi-Kui Hu, Song Zhu, Juan Yang, Zhao Yao, Ping Zhou, Jun Ma","doi":"10.1088/1572-9494/ad595d","DOIUrl":"https://doi.org/10.1088/1572-9494/ad595d","url":null,"abstract":"A gas sensor can convert external gas concentration or species into electric voltage or current signals by physical adsorption or chemical changes. As a result, a gas sensor in a nonlinear circuit can be used as a sensitive sensor for detecting external gas signals from the olfactory system. In this paper, a gas sensor and a field-effect transistor are incorporated into a simple FithzHugh–Nagumo neural circuit for capturing and encoding external gas signals. An improved functional neural circuit is obtained, and the effect of gas concentration, gas species and neuronal activity can be discerned as the gate voltage, threshold voltage and activation coefficient of the field-effect transistor, respectively. The gas concentration can affect the neural activities from quiescent to normal working and, finally, to saturation state in bursting, spiking, periodic and chaotic firings with different frequencies. The effects of gas species and neuronal activity on the firing state can also be achieved in this functional neural circuit. In addition, variations in the gate voltage, threshold voltage and activation coefficient can cause switching between different firing modes. These results can be helpful in designing artificial olfactory devices for bionic gas recognition and other coupled systems arising in applied sciences.","PeriodicalId":10641,"journal":{"name":"Communications in Theoretical Physics","volume":"23 1","pages":""},"PeriodicalIF":3.1,"publicationDate":"2024-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190310","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
Pub Date : 2024-08-16DOI: 10.1088/1572-9494/ad526c
Arzu Akbulut, Waseem Razzaq, Filiz Tascan
In this study, the exact solutions for the propagation of pulses in optical fibers are obtained. Special values are given in the model used, and two nonlinear differential equations are obtained. Nonlinear equations are reduced to ordinary differential equations with the help of wave transformations. Then, the obtained differential equations are solved by two different methods, namely the modified simplest equation and the modified Kudryashov procedures. The solutions are given by hyperbolic, trigonometric and rational functions and the results are useful for optics, engineering and other related areas. Finally three-dimensional, contour and two-dimensional shapes are given for some solutions. These figures are important for understanding the motion of the wave. The given methods are applied to the equations for the first time. To the best of the authors’ knowledge, these results are new and have not been obtained in the literature. The results are useful for applied mathematics, physics and other related areas.
{"title":"Study for obtaining the exact solutions for the propagation of pulses in optical fibers","authors":"Arzu Akbulut, Waseem Razzaq, Filiz Tascan","doi":"10.1088/1572-9494/ad526c","DOIUrl":"https://doi.org/10.1088/1572-9494/ad526c","url":null,"abstract":"In this study, the exact solutions for the propagation of pulses in optical fibers are obtained. Special values are given in the model used, and two nonlinear differential equations are obtained. Nonlinear equations are reduced to ordinary differential equations with the help of wave transformations. Then, the obtained differential equations are solved by two different methods, namely the modified simplest equation and the modified Kudryashov procedures. The solutions are given by hyperbolic, trigonometric and rational functions and the results are useful for optics, engineering and other related areas. Finally three-dimensional, contour and two-dimensional shapes are given for some solutions. These figures are important for understanding the motion of the wave. The given methods are applied to the equations for the first time. To the best of the authors’ knowledge, these results are new and have not been obtained in the literature. The results are useful for applied mathematics, physics and other related areas.","PeriodicalId":10641,"journal":{"name":"Communications in Theoretical Physics","volume":"11 1","pages":""},"PeriodicalIF":3.1,"publicationDate":"2024-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190399","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
Pub Date : 2024-08-16DOI: 10.1088/1572-9494/ad58c2
Yogesh Bhardwaj, C P Singh
We explore the variable generalized Chaplygin gas (VGCG) model in the theory of matter creation cosmology within the framework of a spatially homogeneous and isotropic flat Friedmann—Lemaître—Robertson—Walker space-time. Matter creation cosmology is based on reinterpretation of the energy–momentum tensor in Einstein’s field equations. This creation corresponds to an irreversible energy flow from the gravitational field to the created matter constituents. The variable Chaplygin gas (VCG) is also studied as a particular solution. We use the Markov chain Monte Carlo method to constrain the free parameters of three models, namely, Lambda-Cold-Dark matter (ΛCDM), VGCG and VCG models with and without matter creation from the latest observational data from baryon acoustic oscillations, cosmic chronometer, type Ia supernovae (Pantheon) including gamma-ray bursts, quasars and the local measurement of H0 from R21 data. Two different combinations of dataset provide a fairly tight constraint on the parameters of the ΛCDM, VGCG and VCG models. The present values of various cosmological parameters are obtained, which are very close to the ΛCDM model. Furthermore, we perform stability analysis, Bayesian evidence analysis and information criteria analysis for these models through studying the sound speed, Bayes factor, and Akaike information criteria (AIC) and Bayesian information criteria (BIC) selection criteria. The values of sound speed for VGCG and VCG models shows that both the models are stable. According to AIC, it is observed that VGCG and VCG models with matter creation are supported considerably less by current observations, while BIC shows that these models are not favoured by observational data.
{"title":"Constraining the variable generalized Chaplygin gas model in matter creation cosmology","authors":"Yogesh Bhardwaj, C P Singh","doi":"10.1088/1572-9494/ad58c2","DOIUrl":"https://doi.org/10.1088/1572-9494/ad58c2","url":null,"abstract":"We explore the variable generalized Chaplygin gas (VGCG) model in the theory of matter creation cosmology within the framework of a spatially homogeneous and isotropic flat Friedmann—Lemaître—Robertson—Walker space-time. Matter creation cosmology is based on reinterpretation of the energy–momentum tensor in Einstein’s field equations. This creation corresponds to an irreversible energy flow from the gravitational field to the created matter constituents. The variable Chaplygin gas (VCG) is also studied as a particular solution. We use the Markov chain Monte Carlo method to constrain the free parameters of three models, namely, Lambda-Cold-Dark matter (ΛCDM), VGCG and VCG models with and without matter creation from the latest observational data from baryon acoustic oscillations, cosmic chronometer, type Ia supernovae (Pantheon) including gamma-ray bursts, quasars and the local measurement of <italic toggle=\"yes\">H</italic>\u0000<sub>0</sub> from R21 data. Two different combinations of dataset provide a fairly tight constraint on the parameters of the ΛCDM, VGCG and VCG models. The present values of various cosmological parameters are obtained, which are very close to the ΛCDM model. Furthermore, we perform stability analysis, Bayesian evidence analysis and information criteria analysis for these models through studying the sound speed, Bayes factor, and Akaike information criteria (AIC) and Bayesian information criteria (BIC) selection criteria. The values of sound speed for VGCG and VCG models shows that both the models are stable. According to AIC, it is observed that VGCG and VCG models with matter creation are supported considerably less by current observations, while BIC shows that these models are not favoured by observational data.","PeriodicalId":10641,"journal":{"name":"Communications in Theoretical Physics","volume":"10 1","pages":""},"PeriodicalIF":3.1,"publicationDate":"2024-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190354","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
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