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International Journal of Modern Physics D最新文献

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Timelike Geodesic Congruence in the Simplest Solutions of General Relativity with Quantum-Improved Metric Tensor 广义相对论最简解中量子改进度量张量的类时测地线同余
4区 物理与天体物理
International Journal of Modern Physics D Pub Date : 2023-10-20 DOI: 10.1142/s0218271823500979
A. Nasser Tawfik, T. F. Dabash
{"title":"Timelike Geodesic Congruence in the Simplest Solutions of General Relativity with Quantum-Improved Metric Tensor","authors":"A. Nasser Tawfik, T. F. Dabash","doi":"10.1142/s0218271823500979","DOIUrl":"https://doi.org/10.1142/s0218271823500979","url":null,"abstract":"","PeriodicalId":50307,"journal":{"name":"International Journal of Modern Physics D","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135567745","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
Shadows and photon rings of a spherically accreting Kehagias-Sfetsos black hole 球形吸积Kehagias-Sfetsos黑洞的阴影和光子环
4区 物理与天体物理
International Journal of Modern Physics D Pub Date : 2023-10-18 DOI: 10.1142/s0218271823500888
Mohaddese Heydari-Fard, Malihe Heydari-Fard, Nematollah Riazi
{"title":"Shadows and photon rings of a spherically accreting Kehagias-Sfetsos black hole","authors":"Mohaddese Heydari-Fard, Malihe Heydari-Fard, Nematollah Riazi","doi":"10.1142/s0218271823500888","DOIUrl":"https://doi.org/10.1142/s0218271823500888","url":null,"abstract":"By considering Kehagias–Sfetsos black hole in the framework of the Hořava–Lifshitz gravity, we study the optical appearance of such black holes surrounded by spherical accretion flow. For the static/infalling spherical accretion flow, we compute the observed specific intensity as a function of impact parameter. We also investigate the effect of the Hořava parameter and accreting matter on the luminosity of shadows and photon rings. It is found that an increase in the Hořava parameter decreases the shadow size, while the shadows and photon rings luminosities increase. Moreover, we constrain the Hořava parameter from the observational data reported by the Event Horizon Telescope for M87* and Sgr A*.","PeriodicalId":50307,"journal":{"name":"International Journal of Modern Physics D","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135824011","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: 1
Stability investigations of isotropic and anisotropic exponential inflation in the Starobinsky-Bel-Robinson gravity Starobinsky-Bel-Robinson重力中各向同性和各向异性指数膨胀的稳定性研究
4区 物理与天体物理
International Journal of Modern Physics D Pub Date : 2023-10-17 DOI: 10.1142/s0218271823500876
Tuan Q. Do, Duy H. Nguyen, Tuyen M. Pham
{"title":"Stability investigations of isotropic and anisotropic exponential inflation in the Starobinsky-Bel-Robinson gravity","authors":"Tuan Q. Do, Duy H. Nguyen, Tuyen M. Pham","doi":"10.1142/s0218271823500876","DOIUrl":"https://doi.org/10.1142/s0218271823500876","url":null,"abstract":"In this paper, we would like to examine whether a novel Starobinsky–Bel–Robinson (SBR) gravity model admits stable exponential inflationary solutions with or without spatial anisotropies. As a result, we are able to derive an exact de Sitter inflationary to this SBR model. Furthermore, we observe that an exact Bianchi type I inflationary solution does not exist in the SBR model. However, we find that a modified SBR model, in which the sign of coefficient of [Formula: see text] term is flipped from positive to negative, can admit the corresponding Bianchi type I inflationary solution. Unfortunately, stability analysis using the dynamical system approach indicates that both of these inflationary solutions turn out to be unstable. Interestingly, we show that a stable de Sitter inflationary solution can be obtained in the modified SBR gravity.","PeriodicalId":50307,"journal":{"name":"International Journal of Modern Physics D","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135944968","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: 2
Balancing multiple charge particle excess with baryon asymmetry 用重子不对称平衡多电荷粒子过剩
4区 物理与天体物理
International Journal of Modern Physics D Pub Date : 2023-10-13 DOI: 10.1142/s0218271823400059
Vitaly A. Beylin, Maxim Yu. Khlopov, Danila O. Sopin
{"title":"Balancing multiple charge particle excess with baryon asymmetry","authors":"Vitaly A. Beylin, Maxim Yu. Khlopov, Danila O. Sopin","doi":"10.1142/s0218271823400059","DOIUrl":"https://doi.org/10.1142/s0218271823400059","url":null,"abstract":"","PeriodicalId":50307,"journal":{"name":"International Journal of Modern Physics D","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135918167","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
Drake equation of search for extraterrestrial intelligence: a proposal for modification in the light of Dirac's large number hypothesis 寻找地外智慧的德雷克方程:根据狄拉克大数假设修正的建议
4区 物理与天体物理
International Journal of Modern Physics D Pub Date : 2023-10-13 DOI: 10.1142/s0218271823500943
Saibal Ray, Soham Ray, Issa Al-Amri, S.K. Maurya, K.P. Manith Banula
{"title":"Drake equation of search for extraterrestrial intelligence: a proposal for modification in the light of Dirac's large number hypothesis","authors":"Saibal Ray, Soham Ray, Issa Al-Amri, S.K. Maurya, K.P. Manith Banula","doi":"10.1142/s0218271823500943","DOIUrl":"https://doi.org/10.1142/s0218271823500943","url":null,"abstract":"","PeriodicalId":50307,"journal":{"name":"International Journal of Modern Physics D","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135918627","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
Is it time to rethink quantum gravity? 是时候重新思考量子引力了吗?
4区 物理与天体物理
International Journal of Modern Physics D Pub Date : 2023-10-13 DOI: 10.1142/s0218271823420245
Jonathan Oppenheim
{"title":"Is it time to rethink quantum gravity?","authors":"Jonathan Oppenheim","doi":"10.1142/s0218271823420245","DOIUrl":"https://doi.org/10.1142/s0218271823420245","url":null,"abstract":"Although it's widely believed that gravity should have a quantum nature like every other force, the conceptual obstacles to constructing a quantum theory of gravity compel us to explore other perspectives. Gravity is not like any other force. It alone defines a universal space-time geometry, upon which quantum fields evolve. We feel gravity because matter causes space-time to bend. Time flows at unequal rates at different locations. The rate at which time flows, and the causal structure it provides, may be required to have a classical description in order for quantum theory to be well-formulated. I discuss arguments for this proposition, but ultimately conclude that we must turn to experiment to guide us.","PeriodicalId":50307,"journal":{"name":"International Journal of Modern Physics D","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135918901","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: 1
Normalization of the vacuum and the ultraviolet completion of Einstein gravity 真空归一化和爱因斯坦引力的紫外完成
4区 物理与天体物理
International Journal of Modern Physics D Pub Date : 2023-10-13 DOI: 10.1142/s0218271823500967
Philip D. Mannheim
{"title":"Normalization of the vacuum and the ultraviolet completion of Einstein gravity","authors":"Philip D. Mannheim","doi":"10.1142/s0218271823500967","DOIUrl":"https://doi.org/10.1142/s0218271823500967","url":null,"abstract":"Second-order-derivative plus fourth-order-derivative gravity is the ultraviolet completion of second-order-derivative quantum Einstein gravity. While it achieves renormalizability through states of negative Dirac norm, the unitarity violation that this would entail can be postponed to Planck energies. As we show in this paper the theory has a different problem, one that occurs at all energy scales, namely that the Dirac norm of the vacuum of the theory is not finite. To establish this we present a procedure for determining the norm of the vacuum in any quantum field theory. With the Dirac norm of the vacuum of the second-order-derivative plus fourth-order-derivative theory not being finite, the Feynman rules that are used to establish renormalizability are not valid, as is the assumption that the theory can be used as an effective theory at energies well below the Planck scale. This lack of finiteness is also manifested in the fact that the Minkowski path integral for the theory is divergent. Because the vacuum Dirac norm is not finite, the Hamiltonian of the theory is not Hermitian. However, it turns out to be $PT$ symmetric. And when one continues the theory into the complex plane and uses the $PT$ symmetry inner product, viz. the overlap of the left-eigenstate of the Hamiltonian with its right-eigenstate, one then finds that for the vacuum this norm is both finite and positive, the Feynman rules now are valid, the Minkowski path integral now is well behaved, and the theory now can serve as a low energy effective theory. Consequently, the theory can now be offered as a fully consistent, unitary and renormalizable theory of quantum gravity.","PeriodicalId":50307,"journal":{"name":"International Journal of Modern Physics D","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135918169","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
Charged anisotropic compact stellar models under gravitational Decoupling Scheme 引力解耦方案下的带电各向异性致密恒星模型
4区 物理与天体物理
International Journal of Modern Physics D Pub Date : 2023-09-29 DOI: 10.1142/s0218271823500931
Kiran Pant, Pratibha Fuloria
{"title":"Charged anisotropic compact stellar models under gravitational Decoupling Scheme","authors":"Kiran Pant, Pratibha Fuloria","doi":"10.1142/s0218271823500931","DOIUrl":"https://doi.org/10.1142/s0218271823500931","url":null,"abstract":"","PeriodicalId":50307,"journal":{"name":"International Journal of Modern Physics D","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135192523","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
Foreword 前言
IF 2.2 4区 物理与天体物理
International Journal of Modern Physics D Pub Date : 2023-09-02 DOI: 10.1142/s0218271823020017
Dharam Vir Ahluwalia
{"title":"Foreword","authors":"Dharam Vir Ahluwalia","doi":"10.1142/s0218271823020017","DOIUrl":"https://doi.org/10.1142/s0218271823020017","url":null,"abstract":"","PeriodicalId":50307,"journal":{"name":"International Journal of Modern Physics D","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2023-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45113124","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 viable f(R) gravity model without oscillations in the effective dark energy 有效暗能量无振荡的可行f(R)引力模型
4区 物理与天体物理
International Journal of Modern Physics D Pub Date : 2023-09-01 DOI: 10.1142/s0218271823500864
A. Oliveros
{"title":"A viable <i>f</i>(<i>R</i>) gravity model without oscillations in the effective dark energy","authors":"A. Oliveros","doi":"10.1142/s0218271823500864","DOIUrl":"https://doi.org/10.1142/s0218271823500864","url":null,"abstract":"In this study, we propose a reparametrization of a specific viable [Formula: see text] gravity model to represent it as a perturbation of the [Formula: see text]CDM model. The [Formula: see text] gravity model under consideration includes two parameters, [Formula: see text] and [Formula: see text], which control how close the proposed model can be to [Formula: see text]CDM, allowing for arbitrary proximity. Furthermore, it is shown that the Hu–Sawicki (HS) model is a limiting case of this reparametrized model. Following the existing literature, we also derive an analytical approximation for the expansion rate [Formula: see text], which shows an excellent agreement between this analytical approximation and the numerical solution over a wide range of redshifts for realistic values of the deviation parameter [Formula: see text]. By appropriately selecting values for the model parameters, we plot the cosmological parameters [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text], as well as the statefinder quantities [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text]. We find that their present values (at [Formula: see text]) are consistent with the observations from Planck 2018 and the values predicted by the [Formula: see text]CDM model. It is important to note that the examined cosmological and statefinder parameters do not exhibit significant oscillations of effective dark energy, which could lead to singular and unphysical solutions at high redshifts. This anomalous behavior has been avoided here by utilizing the approximate analytical solution for [Formula: see text]. Additionally, we conduct a detailed analysis of the evolution of matter density perturbations within the introduced [Formula: see text] gravity model. The results demonstrate that this viable [Formula: see text] gravity model is practically indistinguishable from the [Formula: see text]CDM model at the background level.","PeriodicalId":50307,"journal":{"name":"International Journal of Modern Physics D","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135349451","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
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