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Wormhole inducing exponential expansion in R2 gravity 在 R2 引力下诱发指数膨胀的虫洞
IF 1.8 3区 物理与天体物理
International Journal of Geometric Methods in Modern Physics Pub Date : 2024-05-15 DOI: 10.1142/s0219887824502013
B Modak, Gargi Biswas
{"title":"Wormhole inducing exponential expansion in R2 gravity","authors":"B Modak, Gargi Biswas","doi":"10.1142/s0219887824502013","DOIUrl":"https://doi.org/10.1142/s0219887824502013","url":null,"abstract":"<p>Wormholes are considered both from the Wheeler deWitt equation, as well as from the field equations in the Euclidean background of Robertson Walker mini-superspace in <span><math altimg=\"eq-00004.gif\" display=\"inline\" overflow=\"scroll\"><msup><mrow><mi>R</mi></mrow><mrow><mn>2</mn></mrow></msup></math></span><span></span> gravity. Quantum wormhole satisfies Hawking Page wormhole boundary condition in the Euclidean background of mini-superspace, however, in the Lorentzian background wave functional turns to the usual oscillatory function. The Euclidean field equations for <span><math altimg=\"eq-00005.gif\" display=\"inline\" overflow=\"scroll\"><mi>κ</mi><mo>=</mo><mn>0</mn><mo>,</mo><mo stretchy=\"false\">±</mo><mn>1</mn></math></span><span></span> lead to the wormhole configuration, as well as oscillating universe in Euclidean time <span><math altimg=\"eq-00006.gif\" display=\"inline\" overflow=\"scroll\"><mi>τ</mi></math></span><span></span>. The oscillating universe in Euclidean time <span><math altimg=\"eq-00007.gif\" display=\"inline\" overflow=\"scroll\"><mi>τ</mi></math></span><span></span> transforms to an expanding universe only for <span><math altimg=\"eq-00008.gif\" display=\"inline\" overflow=\"scroll\"><mi>κ</mi><mo>=</mo><mn>1</mn></math></span><span></span> in Lorentz time <span><math altimg=\"eq-00009.gif\" display=\"inline\" overflow=\"scroll\"><mi>t</mi></math></span><span></span> under analytic continuation <span><math altimg=\"eq-00010.gif\" display=\"inline\" overflow=\"scroll\"><mi>τ</mi><mo>=</mo><mi>i</mi><mi>t</mi></math></span><span></span> and asymptotically leads to an exponential solution. An Euclidean wormhole in the very early era evolves to an oscillating universe in <span><math altimg=\"eq-00011.gif\" display=\"inline\" overflow=\"scroll\"><mi>τ</mi></math></span><span></span>, thereafter crossing deSitter radius transition to an inflationary era is evident at later epoch only for <span><math altimg=\"eq-00012.gif\" display=\"inline\" overflow=\"scroll\"><mi>κ</mi><mo>=</mo><mn>1</mn></math></span><span></span>.</p>","PeriodicalId":50320,"journal":{"name":"International Journal of Geometric Methods in Modern Physics","volume":"47 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141091907","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}
引用次数: 0
Potentials on the conformally compactified Minkowski spacetime and their application to quark deconfinement 共形压缩闵科夫斯基时空中的势及其在夸克去冲突中的应用
IF 1.8 3区 物理与天体物理
International Journal of Geometric Methods in Modern Physics Pub Date : 2024-05-15 DOI: 10.1142/s0219887824501913
M. Kirchbach, J. A. Vallejo
{"title":"Potentials on the conformally compactified Minkowski spacetime and their application to quark deconfinement","authors":"M. Kirchbach, J. A. Vallejo","doi":"10.1142/s0219887824501913","DOIUrl":"https://doi.org/10.1142/s0219887824501913","url":null,"abstract":"<p>In this paper, we study a class of conformal metric deformations in the quasi-radial coordinate parametrizing the three-sphere in the conformally compactified Minkowski spacetime <span><math altimg=\"eq-00001.gif\" display=\"inline\" overflow=\"scroll\"><msup><mrow><mi>S</mi></mrow><mrow><mn>1</mn></mrow></msup><mo stretchy=\"false\">×</mo><msup><mrow><mi>S</mi></mrow><mrow><mn>3</mn></mrow></msup></math></span><span></span>. Prior to reduction of the associated Laplace–Beltrami operators to a Schrödinger form, a corresponding class of exactly solvable potentials (each one containing a scalar and a gradient term) is found. In particular, the scalar piece of these potentials can be exactly or quasi-exactly solvable, and among them we find the finite range confining trigonometric potentials of Pöschl–Teller, Scarf and Rosen–Morse. As an application of the results developed in the paper, the large compactification radius limit of the interaction described by some of these potentials is studied, and this regime is shown to be relevant to a quantum mechanical quark deconfinement mechanism.</p>","PeriodicalId":50320,"journal":{"name":"International Journal of Geometric Methods in Modern Physics","volume":"67 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141092021","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}
引用次数: 0
Cosmological solutions in the Brans–Dicke theory via invariants of symmetry groups 布兰士-迪克理论中通过对称群不变式的宇宙学解决方案
IF 1.8 3区 物理与天体物理
International Journal of Geometric Methods in Modern Physics Pub Date : 2024-05-09 DOI: 10.1142/s0219887824501925
E. Ahmadi-Azar, K. Atazadeh, A. Eghbali
{"title":"Cosmological solutions in the Brans–Dicke theory via invariants of symmetry groups","authors":"E. Ahmadi-Azar, K. Atazadeh, A. Eghbali","doi":"10.1142/s0219887824501925","DOIUrl":"https://doi.org/10.1142/s0219887824501925","url":null,"abstract":"<p>We proceed to obtain an exact analytical solution of the Brans–Dicke (BD) equations for the spatially flat (<span><math altimg=\"eq-00001.gif\" display=\"inline\" overflow=\"scroll\"><mi>k</mi><mo>=</mo><mn>0</mn></math></span><span></span>) Friedmann–Lamaître–Robertson–Walker (FLRW) cosmological model in both cases of the absence and presence of the cosmological constant. The solution method that we use to solve the field equations of the BD equations is called the “invariants of symmetry groups method” (ISG method). This method is based on the extended Prelle–Singer (PS) method and it employs the Lie point symmetries, <span><math altimg=\"eq-00002.gif\" display=\"inline\" overflow=\"scroll\"><mi>λ</mi></math></span><span></span>-symmetries, and Darboux polynomials (DPs). Indeed, the ISG method tries to provide two independent first-order invariants associated to the one-parameter Lie groups of transformations keeping the ordinary differential equations (ODEs) invariant, as solutions. It should be noted for integrable ODEs that the ISG method guarantees the extraction of these two invariants. In this work, for the BD equations in FLRW cosmological model, we find the Lie point symmetries, <span><math altimg=\"eq-00003.gif\" display=\"inline\" overflow=\"scroll\"><mi>λ</mi></math></span><span></span>-symmetries, and DPs, and obtain the basic quantities of the extended PS method (which are the null forms and the integrating factors). By making use of the extended PS method we find two independent first-order invariants in such a way that appropriate cosmological solutions from solving these invariants as a system of algebraic equations are simultaneously obtained. These solutions are wealthy in that they include many known special solutions, such as the O’Hanlon–Tupper vacuum solutions, Nariai’s solutions, Brans–Dicke dust solutions, inflationary solutions, etc.</p>","PeriodicalId":50320,"journal":{"name":"International Journal of Geometric Methods in Modern Physics","volume":"18 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140919788","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}
引用次数: 0
Space-time entropy, space of singularities and gravity origin: A case study 时空熵、奇点空间和引力起源：案例研究
IF 1.8 3区 物理与天体物理
International Journal of Geometric Methods in Modern Physics Pub Date : 2024-04-30 DOI: 10.1142/s0219887824501895
Fayçal Ben Adda
{"title":"Space-time entropy, space of singularities and gravity origin: A case study","authors":"Fayçal Ben Adda","doi":"10.1142/s0219887824501895","DOIUrl":"https://doi.org/10.1142/s0219887824501895","url":null,"abstract":"<p>A new definition of entropy is introduced using a model that simulates an expanding space-time compatible with the fundamental principle of cosmology. The entropy is obtained by mean of a state function that measures the variation of the space-time normal curvature, from a highly compressed space to a lower compressed space. The defined entropy leads to work out a new understanding of the earliest conditions that last for a period estimated to 380,000 years after the Big Bang. It leads to understand via a short period of inflation the process that generates the uniform distribution of matter and energy at the surface of the last scattering. It involves gravitational singularities in a process of gradual decompression propitious to the incubation of matter recombination, and it allows to trace back gravity origin.</p>","PeriodicalId":50320,"journal":{"name":"International Journal of Geometric Methods in Modern Physics","volume":"15 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140819289","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}
引用次数: 0
Structural properties of compact stars in extended Teleparallel gravity 扩展遥平行引力下紧凑恒星的结构特性
IF 1.8 3区 物理与天体物理
International Journal of Geometric Methods in Modern Physics Pub Date : 2024-04-22 DOI: 10.1142/s0219887824501615
Asifa Ashraf, Faisal Javed, Wen-Xiu Ma, G. Mustafa
{"title":"Structural properties of compact stars in extended Teleparallel gravity","authors":"Asifa Ashraf, Faisal Javed, Wen-Xiu Ma, G. Mustafa","doi":"10.1142/s0219887824501615","DOIUrl":"https://doi.org/10.1142/s0219887824501615","url":null,"abstract":"<p>In this study, the structures of stars are examined using the Karmarkar condition (KC) to assess the metric components. The study also takes into account the anisotropic source of the matter distribution in the context of Modified Teleparallel Rastall Gravity (MTRG). Various values of the model parameter <span><math altimg=\"eq-00001.gif\" display=\"inline\" overflow=\"scroll\"><mi>η</mi></math></span><span></span> are tested by assuming different metric coefficients for the embedding spacetime. To calculate the involved model parameters, the Schwarzschild black hole solution is employed as an exterior solution. The stability and admissibility of the solutions obtained are demonstrated by analyzing some core properties of stellar objects, using observed data from established stellar models such as “PSRJ1416-2230”. It is worth noting that the results obtained in this study are physically feasible and acceptable.</p>","PeriodicalId":50320,"journal":{"name":"International Journal of Geometric Methods in Modern Physics","volume":"88 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140637647","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}
引用次数: 0
Gravitational lensing in a spacetime with cosmic string within the Eddington-inspired Born–Infeld gravity 在爱丁顿启发的博恩-因费尔德引力范围内的宇宙弦时空中的引力透镜效应
IF 1.8 3区 物理与天体物理
International Journal of Geometric Methods in Modern Physics Pub Date : 2024-04-22 DOI: 10.1142/s0219887824501871
Faizuddin Ahmed
{"title":"Gravitational lensing in a spacetime with cosmic string within the Eddington-inspired Born–Infeld gravity","authors":"Faizuddin Ahmed","doi":"10.1142/s0219887824501871","DOIUrl":"https://doi.org/10.1142/s0219887824501871","url":null,"abstract":"<p>This study explores the deflection angle of photon rays or light-like geodesics within the framework of Eddington-inspired Born–Infeld (EiBI) gravity background space-time, taking into account the influence of cosmic strings. The primary focus lies in deriving the effective potential of the system applicable to both null and time-like geodesics, as well as determining the angle of deflection for light-like geodesics. Our analysis shows that the presence of cosmic strings induces modifications in these physical quantities, leading to shifts in their respective values.</p>","PeriodicalId":50320,"journal":{"name":"International Journal of Geometric Methods in Modern Physics","volume":"142 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140637509","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}
引用次数: 0
Remarks on the global monopole topological effects on spherical symmetric potentials 关于球对称势的全局单极拓扑效应的评论
IF 1.8 3区 物理与天体物理
International Journal of Geometric Methods in Modern Physics Pub Date : 2024-04-22 DOI: 10.1142/s0219887824501883
K. Bakke
{"title":"Remarks on the global monopole topological effects on spherical symmetric potentials","authors":"K. Bakke","doi":"10.1142/s0219887824501883","DOIUrl":"https://doi.org/10.1142/s0219887824501883","url":null,"abstract":"<p>In this paper, we study the topological effects of the global monopole spacetime on the energy eigenvalues of spherical symmetric potentials in the nonrelativistic regime. We deal with the radial equation by using the Wentzel, Kramers and Brillouim (WKB) approximation. In the cases where the energy levels of the <span><math altimg=\"eq-00001.gif\" display=\"inline\" overflow=\"scroll\"><mi>ℓ</mi></math></span><span></span>-waves can be achieved, the WKB approximation is used based on the Langer transformation.</p>","PeriodicalId":50320,"journal":{"name":"International Journal of Geometric Methods in Modern Physics","volume":"96 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140637701","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}
引用次数: 0
Motion of test particles in quasi anti-de Sitter regular black holes 准反德西特正态黑洞中测试粒子的运动
IF 1.8 3区 物理与天体物理
International Journal of Geometric Methods in Modern Physics Pub Date : 2024-04-09 DOI: 10.1142/s021988782440019x
Dario Corona, Roberto Giambò, Orlando Luongo
{"title":"Motion of test particles in quasi anti-de Sitter regular black holes","authors":"Dario Corona, Roberto Giambò, Orlando Luongo","doi":"10.1142/s021988782440019x","DOIUrl":"https://doi.org/10.1142/s021988782440019x","url":null,"abstract":"<p>In this paper, we explore the characteristics of two novel regular spacetimes that exhibit a nonzero vacuum energy term, under the form of a (quasi) anti-de Sitter phase. Specifically, the first metric is spherical, while the second, derived by applying the generalized Newman–Janis algorithm to the first, is axisymmetric. We show that the equations of state of the effective fluids associated with the two metrics asymptotically tend to negative values, resembling quintessence. In addition, we study test particle motions, illustrating the main discrepancies among our models and more conventional metrics exhibiting non-vanishing anti-de Sitter phase.</p>","PeriodicalId":50320,"journal":{"name":"International Journal of Geometric Methods in Modern Physics","volume":"47 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140538516","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}
引用次数: 0
A revisit to classical and quantum aspects of Raychaudhuri equation and possible resolution of singularity 重温雷乔杜里方程的经典和量子方面以及奇异性的可能解决方案
IF 1.8 3区 物理与天体物理
International Journal of Geometric Methods in Modern Physics Pub Date : 2024-03-26 DOI: 10.1142/s0219887824400188
Subenoy Chakraborty, Madhukrishna Chakraborty
{"title":"A revisit to classical and quantum aspects of Raychaudhuri equation and possible resolution of singularity","authors":"Subenoy Chakraborty, Madhukrishna Chakraborty","doi":"10.1142/s0219887824400188","DOIUrl":"https://doi.org/10.1142/s0219887824400188","url":null,"abstract":"<p>In this review, we provide a concrete overview of the Raychaudhuri equation, Focusing Theorem and convergence conditions in a plethora of backgrounds and discuss the consequences. We also present various classical and quantum approaches suggested in the literature that could potentially mitigate the initial big-bang singularity and the black-hole singularity.</p>","PeriodicalId":50320,"journal":{"name":"International Journal of Geometric Methods in Modern Physics","volume":"32 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140310701","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}
引用次数: 0
Geometric phase for two-mode entangled squeezed-coherent states 双模纠缠挤相干态的几何相位
IF 1.8 3区 物理与天体物理
International Journal of Geometric Methods in Modern Physics Pub Date : 2024-03-25 DOI: 10.1142/s0219887824501470
S. Mohammadi Almas, G. Najarbashi, A. Tavana
{"title":"Geometric phase for two-mode entangled squeezed-coherent states","authors":"S. Mohammadi Almas, G. Najarbashi, A. Tavana","doi":"10.1142/s0219887824501470","DOIUrl":"https://doi.org/10.1142/s0219887824501470","url":null,"abstract":"<p>In this paper, we investigate the geometric phase (GP) of two-mode entangled squeezed-coherent states (ESCSs), undergoing unitary cyclic evolution. Results show that increasing the squeezing parameter of either mode of the balanced ESCS compresses the GP elliptically with respect to the coherence parameter of the corresponding mode. While in the case of unbalanced ESCS, the GP is compressed hyperbolically by increasing the squeezing parameters of the either mode. By generalizing the approach to higher constituting-state dimensions, it is found that the GPs of both balanced and unbalanced ESCSs, increase for a specific value of the coherence parameter. By analyzing the states through the Schmidt decomposition method, we find that, locally, the balanced and unbalanced ESCSs are unitarily equivalent. Finally, based on the interferometry technique, we suggest a theoretical scheme for the physical generation of ESCSs.</p>","PeriodicalId":50320,"journal":{"name":"International Journal of Geometric Methods in Modern Physics","volume":"10 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140209736","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}
引用次数: 0
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