Modern Physics Letters A最新文献

A new kind of Robe’s problem with charged bodies 罗布的新型带电体问题

IF 1.5 4区物理与天体物理

Modern Physics Letters A Pub Date : 2024-07-26 DOI: 10.1142/s0217732324500950

Preeti Yadav, Abdullah, Sada Nand Prasad

引用次数: 0

Reconsidering bulk viscosity in Brans–Dicke theory 重新考虑布兰士-迪克理论中的体积粘度

IF 1.5 4区物理与天体物理

Modern Physics Letters A Pub Date : 2024-07-23 DOI: 10.1142/s0217732324501050

Kanchan Devi, Pankaj Kumar

{"title":"Reconsidering bulk viscosity in Brans–Dicke theory","authors":"Kanchan Devi, Pankaj Kumar","doi":"10.1142/s0217732324501050","DOIUrl":"https://doi.org/10.1142/s0217732324501050","url":null,"abstract":"In this paper, we reconsider the concept of bulk viscosity in Brans–Dicke theory to study accelerated expansion of the universe in a flat Friedmann–Robertson–Walker metric. In recent works on bulk viscosity in Brans–Dicke theory, the power-law form of Brans–Dicke scalar field has been taken to explain recent phase transition of the universe, however, power-law form confronts constant deceleration parameter problem. Therefore, we consider recently proposed well-motivated logarithmic form of Brans–Dicke scalar field to discuss bulk viscous model in Brans–Dicke theory. We obtain the values of deceleration parameter and equation of state parameter for the model, and plot their graphs against the redshift parameter z. The plots show that the model is able to explain the recent phase transition of the universe and equation of state parameter shows the behavior of dark energy. Further, we apply two important analysis, namely, [Formula: see text] analysis and thermodynamic analysis to examine our model. The [Formula: see text] analysis shows that our model belong to thawing region and shows similarities with quintessence model. All the trajectories start from the point [Formula: see text] with different negative values of w having quintessence behavior. The thermodynamic analysis shows that the model satisfies generalized second law of thermodynamics.","PeriodicalId":18752,"journal":{"name":"Modern Physics Letters A","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2024-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141813573","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}

引用次数: 0

Quintessential f(G) gravity with statistically fitting of H(z) 统计拟合 H(z) 的五重 f(G) 引力

IF 1.5 4区物理与天体物理

Modern Physics Letters A Pub Date : 2024-07-23 DOI: 10.1142/s0217732324500998

S. Shekh, A. Husain, H. Chaudhary, S. Samdurkar, N. Myrzakulov

{"title":"Quintessential f(G) gravity with statistically fitting of H(z)","authors":"S. Shekh, A. Husain, H. Chaudhary, S. Samdurkar, N. Myrzakulov","doi":"10.1142/s0217732324500998","DOIUrl":"https://doi.org/10.1142/s0217732324500998","url":null,"abstract":"Inspired by high-energy physics and by considering standard gravity theory as the low-energy limit of quantum theory, the modification of general relativity as [Formula: see text] has been proposed. This paper is dedicated to investigating the cosmological model of modified Gauss–Bonnet gravity in four dimensions. General field equations for the four-dimensional Friedmann– Robertson–Walker metric are given in detail. Also, it is well known that Hubble parameter [Formula: see text] measurements are helpful for the inference of cosmological model parameters. We try to explain the MCMC statistical approach used to calculate Hubble’s parameter. The resulting form of [Formula: see text] was limited using Cosmic Chronometric data, Standard Candles SN Ia from Pantheon, and Baryon Acoustic Oscillations to obtain the best match values by using the regression equation. Finally, to examine the late-time dynamics of our Universe, the behavior of physical and kinematic variables like the deceleration parameter [Formula: see text], State-finder parameters [Formula: see text], diagnostic parameter ([Formula: see text]), equation of state parameter as well as the behavior of energy conditions versus redshift with the parameter values are presented.","PeriodicalId":18752,"journal":{"name":"Modern Physics Letters A","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2024-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141813816","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}

引用次数: 0

Circular motions and electromagnetic properties in the magnetized Kaluza–Klein spacetime 磁化卡卢扎-克莱因时空中的圆周运动和电磁特性

IF 1.5 4区物理与天体物理

Modern Physics Letters A Pub Date : 2024-07-19 DOI: 10.1142/s0217732324501025

H. M. Siahaan

引用次数: 0

Significance of a quadratically varying deceleration parameter in scalar field-dominated model and cosmic acceleration 标量场主导模型和宇宙加速中二次变化减速参数的意义

IF 1.5 4区物理与天体物理

Modern Physics Letters A Pub Date : 2024-07-16 DOI: 10.1142/s0217732324500871

K. R. Mishra, H. Chaudhary, Rajesh Kumar, Z. Nekouee, S. Pacif

{"title":"Significance of a quadratically varying deceleration parameter in scalar field-dominated model and cosmic acceleration","authors":"K. R. Mishra, H. Chaudhary, Rajesh Kumar, Z. Nekouee, S. Pacif","doi":"10.1142/s0217732324500871","DOIUrl":"https://doi.org/10.1142/s0217732324500871","url":null,"abstract":"In this study, we explore the enigma of late-time cosmic acceleration in the framework of a general scalar field playing the role of dark energy. Our investigation yields an exact solution to Einstein’s field equations, achieved through a parametrization of the deceleration parameter [Formula: see text] in quadratic form in the homogeneous and isotropic background geometry represented by Friedmann–Lemaître–Robertson–Walker (FLRW) spacetime. This parametrization unveils a seamless transition from a decelerated to an accelerated phase in the cosmic evolution. Furthermore, we leverage this parametrization to reconstruct cosmological parameters with respect to redshift z, elucidating their dependency on certain model parameters that govern the universe’s evolutionary trajectory. The model parameters are subsequently constrained using diverse observational datasets. We provide a comprehensive analysis of the evolution of geometrical and physical parameters, complete with the numerically constrained values. To gain deeper insights into the nature of dark energy, we employ Statefinder diagnostics, conducting a thorough examination. Our findings shed light on the intricate interplay between cosmic acceleration, quintessential dark energy and the parametrization of deceleration parameter, offering valuable insights into the fundamental dynamics of the universe.","PeriodicalId":18752,"journal":{"name":"Modern Physics Letters A","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2024-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141832302","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}

引用次数: 0

Behavior of Tsallis holographic dark energy for Marder universe 马德尔宇宙的查里斯全息暗能量行为

IF 1.5 4区物理与天体物理

Modern Physics Letters A Pub Date : 2024-07-16 DOI: 10.1142/s0217732324501049

C. Aktaş

{"title":"Behavior of Tsallis holographic dark energy for Marder universe","authors":"C. Aktaş","doi":"10.1142/s0217732324501049","DOIUrl":"https://doi.org/10.1142/s0217732324501049","url":null,"abstract":"In this study, Tsallis holographic dark energy (THDE) was discussed within the frame of [Formula: see text] gravitational theory and considering the homogeneous and anisotropic Marder universe. The Hubble horizon was taken into consideration as infrared cutoff of the system. To get the field equations, solutions were used for the THDE density and the anisotropy parameter. Furthermore, a variety of physical parameters such as deceleration parameter, anisotropy parameter and volume have been examined. They have been also been visually examined with the help of graphics. Different values of deceleration parameter consistent with different observational data were mentioned. In addition to this, cosmological parameters like jerk, lerk and snap parameters were analyzed. Statefinder diagnostics which are helpful tools for the separation of dark energy models have been examined. By the calculation and representation of the overall density parameter ([Formula: see text]) it can be concluded that the anisotropic nature of model vanishes showing a tendency to isotropy in accordance with present universe. Finally, the physical and geometrical nature of the model was studied, collating with relevant studies and observations.","PeriodicalId":18752,"journal":{"name":"Modern Physics Letters A","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2024-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141832385","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}

引用次数: 0

Studies on Bianchi type-III cosmological model with parametrization of deceleration parameter in a SBST theory 带 SBST 理论中减速参数参数化的比安奇 III 型宇宙学模型研究

IF 1.5 4区物理与天体物理

Modern Physics Letters A Pub Date : 2024-07-16 DOI: 10.1142/s0217732324500937

Kangujam Priyokumar Singh, A. J. Meitei

引用次数: 0

Background gravitational waves as signature of the accelerated cosmic expansion 作为宇宙加速膨胀特征的背景引力波

IF 1.5 4区物理与天体物理

Modern Physics Letters A Pub Date : 2024-07-16 DOI: 10.1142/s0217732324500974

Cláudio Nassif Cruz, A. C. A. de Faria

{"title":"Background gravitational waves as signature of the accelerated cosmic expansion","authors":"Cláudio Nassif Cruz, A. C. A. de Faria","doi":"10.1142/s0217732324500974","DOIUrl":"https://doi.org/10.1142/s0217732324500974","url":null,"abstract":"We propose a toy model of a spherical universe made up of an exotic dark gas with temperature T in thermal equilibrium with a black-body in adiabatic expansion. Each particle of this exotic gas mimics a kind of particle of dark energy. So, each dark particle occupies a very small area of space so-called Planck area [Formula: see text], which represents the minimum area of the whole space-time given by the spherical surface with area [Formula: see text], where [Formula: see text] is the Hubble radius. We realize that such spherical surface is the surface of the black-body for representing the dark universe as if it were the surface of an expanding balloon. Thus, we are able to derive the law of universal gravitation, thus leading us to understand the cosmological anti-gravity. We estimate the tiny order of magnitude of the cosmological constant and the acceleration of expansion of the dark sphere. In this toy model, as the dark universe can be thought of as a large black body, when we obtain its power and frequency of emission of radiation, we find very low values. We conclude that such radiation and frequency of the black body made up of dark energy is a background gravitational wave with very low frequency in the order of [Formula: see text] due to the slight stretching of the fabric of space-time.","PeriodicalId":18752,"journal":{"name":"Modern Physics Letters A","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2024-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141832592","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}

引用次数: 0

A cosmological model formulated in Lyra geometry incorporating Ricci dark energy and a deceleration parameter that varies linearly 以天琴座几何学建立的宇宙学模型，包含利玛窦暗能量和线性变化的减速参数

IF 1.4 4区物理与天体物理

Modern Physics Letters A Pub Date : 2024-06-14 DOI: 10.1142/s0217732324500615

A. Alkaoud, M. Bakry, A. Eid, M. Khader

引用次数: 0

Soliton waves with optical solutions to the three-component coupled nonlinear Schrödinger equation 三分量耦合非线性薛定谔方程光学解的孤子波

IF 1.4 4区物理与天体物理

Modern Physics Letters A Pub Date : 2024-06-11 DOI: 10.1142/s0217732324500688

Karmina K. Ali, Abdullahi Yusuf

引用次数: 0