Pub Date : 2024-07-04DOI: 10.1007/s10714-024-03261-5
Laurenţiu Bubuianu, Julia O. Seti, Sergiu I. Vacaru, Elşen Veli Veliev
We elaborate on a model of nonassociative and noncommutative Einstein–Dirac–Maxwell, EDM, theory determined by star product R-flux deformations in string theory. Solutions for nonassociative EDM systems and physical properties not studied in modern physics. For modifications of the four-dimensional, 4-d, Einstein gravity, we work on conventional nonassociative 8-d phase spaces modelled as star-deformed co-tangent Lorentz bundles. Generalizing the anholonomic frame and connection deformation method, the nonassociative EDM equations are decoupled and integrated in exact and parametric quasi-stationary forms. Corresponding generic off-diagonal metrics are described by nonlinear symmetries and encode nonassociative effective sources and generating functions depending on space and momentum-like coordinates. For respective nonholonomic parameterizations, such solutions describe nonassociative deformations of the Reissner–Nordström black holes. A variant of nonassociative phase space wormhole solution with fermions possessing anisotropic polarized masses is also analyzed. We conclude that such phase space physical objects can’t be characterized using the concept of Bekenstein–Hawking entropy and show how to compute another type (modified G. Perelman ones) nonassociative geometric and statistical thermodynamic variables.
我们详细阐述了弦理论中由星积 R 流变形决定的非共轭和非交换爱因斯坦-狄拉克-麦克斯韦(EDM)理论模型。非共轭 EDM 系统的解和现代物理学中未研究的物理特性。对于四维(4-d)爱因斯坦引力的修正,我们以星形变形共切洛伦兹束为模型,研究传统的非关联 8-d 相空间。通过推广符合人体工程学的框架和连接变形方法,非耦合 EDM 方程被解耦,并以精确和参数准静态形式进行积分。相应的通用非对角度量由非线性对称性描述,并根据空间和类动量坐标编码非耦合有效源和生成函数。对于各自的非整体参数化,这些解描述了赖斯纳-诺德斯特伦黑洞的非耦合变形。我们还分析了具有各向异性极化质量的费米子的非耦合相空间虫洞解决方案的变体。我们得出结论,这种相空间物理对象不能用贝肯斯坦-霍金熵的概念来表征,并展示了如何计算另一种类型(修正的 G. 佩雷尔曼类型)的非关联几何和统计热力学变量。
{"title":"Nonassociative Einstein–Dirac–Maxwell systems and R-flux modified Reissner–Nordström black holes and wormholes","authors":"Laurenţiu Bubuianu, Julia O. Seti, Sergiu I. Vacaru, Elşen Veli Veliev","doi":"10.1007/s10714-024-03261-5","DOIUrl":"https://doi.org/10.1007/s10714-024-03261-5","url":null,"abstract":"<p>We elaborate on a model of nonassociative and noncommutative Einstein–Dirac–Maxwell, EDM, theory determined by star product R-flux deformations in string theory. Solutions for nonassociative EDM systems and physical properties not studied in modern physics. For modifications of the four-dimensional, 4-d, Einstein gravity, we work on conventional nonassociative 8-d phase spaces modelled as star-deformed co-tangent Lorentz bundles. Generalizing the anholonomic frame and connection deformation method, the nonassociative EDM equations are decoupled and integrated in exact and parametric quasi-stationary forms. Corresponding generic off-diagonal metrics are described by nonlinear symmetries and encode nonassociative effective sources and generating functions depending on space and momentum-like coordinates. For respective nonholonomic parameterizations, such solutions describe nonassociative deformations of the Reissner–Nordström black holes. A variant of nonassociative phase space wormhole solution with fermions possessing anisotropic polarized masses is also analyzed. We conclude that such phase space physical objects can’t be characterized using the concept of Bekenstein–Hawking entropy and show how to compute another type (modified G. Perelman ones) nonassociative geometric and statistical thermodynamic variables.</p>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141521457","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}
Pub Date : 2024-07-02DOI: 10.1007/s10714-024-03267-z
Rabia Saleem, Shan Ali, M. Israr Aslam
This article explores the characteristics of interacting new Tsallis agegraphic dark energy (NTADE) and Sharma–Mittal holographic dark energy (SMHDE) models in a flat FLRW universe within Rastall gravity (RG). To check the viability of these models and to distinguish them, we develop important cosmological parameters including equation of state (EoS) parameter, deceleration parameter q, square speed of sound, statefinder pair and Om(z) diagnostic. By constraining the different parameters for both dark energy (DE) models, it is observed that: EoS parameter indicates phantom-like behavior, deceleration parameter is showing a phase transition from decelerating to accelerating phase. The (j, s) plane is indicating a rich behavior as it shows different DE eras like quintessence, phantom and Chaplygin gas for both models depending upon interacting term (d^{2}), parameter (delta ) and Rastall parameter (lambda ). The (omega _{D}-omega ^{'}_{D}) pair is indicating freezing region for NTADE but for SMHDE it initially falls in freezing region then move towards thawing region. We also check stability of NTADE/SMHDE models through the graphical interpretation of square speed of sound.
{"title":"A study of interacting NTADE and SMHDE models via cosmological parameters within rastall gravity","authors":"Rabia Saleem, Shan Ali, M. Israr Aslam","doi":"10.1007/s10714-024-03267-z","DOIUrl":"https://doi.org/10.1007/s10714-024-03267-z","url":null,"abstract":"<p>This article explores the characteristics of interacting new Tsallis agegraphic dark energy (NTADE) and Sharma–Mittal holographic dark energy (SMHDE) models in a flat FLRW universe within Rastall gravity (RG). To check the viability of these models and to distinguish them, we develop important cosmological parameters including equation of state (EoS) parameter, deceleration parameter <i>q</i>, square speed of sound, statefinder pair and <i>Om</i>(<i>z</i>) diagnostic. By constraining the different parameters for both dark energy (DE) models, it is observed that: EoS parameter indicates phantom-like behavior, deceleration parameter is showing a phase transition from decelerating to accelerating phase. The (<i>j</i>, <i>s</i>) plane is indicating a rich behavior as it shows different DE eras like quintessence, phantom and Chaplygin gas for both models depending upon interacting term <span>(d^{2})</span>, parameter <span>(delta )</span> and Rastall parameter <span>(lambda )</span>. The <span>(omega _{D}-omega ^{'}_{D})</span> pair is indicating freezing region for NTADE but for SMHDE it initially falls in freezing region then move towards thawing region. We also check stability of NTADE/SMHDE models through the graphical interpretation of square speed of sound.</p>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141495890","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}
Pub Date : 2024-07-02DOI: 10.1007/s10714-024-03264-2
A. S. Alam, L. C. Andaru, B. N. Jayawiguna, H. S. Ramadhan
We conduct a comprehensive study on spherical orbits around two types of black holes: Kerr–Newman black holes, which are charged, and Ghosh black holes, which are nonsingular. In this work, we consider both null and timelike cases of orbits. Utilizing the Mino formalism, all analytical solutions for the geodesics governing these orbits can be obtained. It turns out that all spherical photon orbits outside the black hole horizons are unstable. In the extremal cases of both models, we obtain the photon boomerangs. The existence of charge in the Kerr–Newman allows the orbits to transition between retrograde and prograde motions, and its increase tends to force the orbits to be more equatorial. On the other hand, the Ghosh black hole, characterized by a regular core and a lack of horizons in certain conditions, presents the possibility of observable stable spherical orbits in the so-called no-horizon condition. As the Ghosh parameter k increases, trajectories tend to exhibit larger latitudinal oscillation amplitudes. We observe that as the Ghosh parameter k increases the trajectories tend to have larger latitudinal oscillation amplitudes. Finally, we investigate the existence of innermost stable spherical orbits (ISSOs). Both black holes demonstrate the appearance of two branches of ISSO radii as a function of the Carter constant ({mathcal {C}}). However, there are notable differences in their behavior: in the case of the Kerr–Newman black hole, the branches merge at a critical value, beyond which no ISSO exists, while for the Ghosh black hole, the transcendental nature of the metric function causes the branches to become complex at some finite distance.
我们对两类黑洞周围的球形轨道进行了全面研究:带电的克尔-纽曼黑洞和不带电的戈什黑洞。在这项工作中,我们考虑了轨道的空和时间两种情况。利用米诺形式主义,我们可以得到支配这些轨道的大地线的所有解析解。结果表明,黑洞视界之外的所有球形光子轨道都是不稳定的。在这两种模型的极端情况下,我们得到了光子回旋镖。克尔-纽曼模型中电荷的存在允许轨道在逆行和顺行之间转换,电荷的增加会迫使轨道更加赤道化。另一方面,戈什黑洞的特点是内核规整,在某些条件下没有地平线,因此在所谓的无地平线条件下有可能出现可观测的稳定球形轨道。随着戈什参数 k 的增大,轨迹往往会表现出更大的纬度振荡幅度。我们观察到,随着戈什参数 k 的增大,轨迹往往具有更大的纬度振荡振幅。最后,我们研究了最内层稳定球形轨道(ISSO)的存在。两个黑洞都显示出ISSO半径的两个分支是卡特常数({mathcal {C}}/)的函数。然而,它们的行为存在显著差异:在克尔-纽曼黑洞中,分支在一个临界值处合并,超过这个临界值就不存在ISSO了;而在戈什黑洞中,度量函数的超越性质导致分支在某个有限距离处变得复杂。
{"title":"Spherical orbits around Kerr–Newman and Ghosh black holes","authors":"A. S. Alam, L. C. Andaru, B. N. Jayawiguna, H. S. Ramadhan","doi":"10.1007/s10714-024-03264-2","DOIUrl":"https://doi.org/10.1007/s10714-024-03264-2","url":null,"abstract":"<p>We conduct a comprehensive study on spherical orbits around two types of black holes: Kerr–Newman black holes, which are charged, and Ghosh black holes, which are nonsingular. In this work, we consider both null and timelike cases of orbits. Utilizing the Mino formalism, all analytical solutions for the geodesics governing these orbits can be obtained. It turns out that all spherical photon orbits outside the black hole horizons are unstable. In the extremal cases of both models, we obtain the <i>photon boomerangs</i>. The existence of charge in the Kerr–Newman allows the orbits to transition between retrograde and prograde motions, and its increase tends to force the orbits to be more equatorial. On the other hand, the Ghosh black hole, characterized by a regular core and a lack of horizons in certain conditions, presents the possibility of observable stable spherical orbits in the so-called <i>no-horizon</i> condition. As the Ghosh parameter <i>k</i> increases, trajectories tend to exhibit larger latitudinal oscillation amplitudes. We observe that as the Ghosh parameter <i>k</i> increases the trajectories tend to have larger latitudinal oscillation amplitudes. Finally, we investigate the existence of <i>innermost stable spherical orbits</i> (ISSOs). Both black holes demonstrate the appearance of two branches of ISSO radii as a function of the Carter constant <span>({mathcal {C}})</span>. However, there are notable differences in their behavior: in the case of the Kerr–Newman black hole, the branches merge at a critical value, beyond which no ISSO exists, while for the Ghosh black hole, the transcendental nature of the metric function causes the branches to become complex at some finite distance.</p>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141495944","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}
Pub Date : 2024-07-01DOI: 10.1007/s10714-024-03266-0
R. Baghbani, M. Dehghani
For the ((n+1))-dimensional ((nge 3)) dilaton black hole in the Einstein–Maxwell-dilaton theory, we have presented exact analytical solutions of the field equations. These exact solutions include the exact formula of the potential function as well as the exact formula of the metric function. The presence of the dilaton field makes the asymptotic behavior of these black holes no longer flat or anti-de Sitter. We have calculated the electric charge, mass, temperature, entropy and electric potential of these black holes and have shown the correctness of the first law of black hole thermodynamics. As a thermodynamic system, we have analyzed thermal stability of these types of black holes using the canonical ensemble method and, investigated the effect of dilaton field on their stability.
{"title":"New exact solutions, thermodynamics and phase transition in the Einstein–Maxwell-dilaton theory","authors":"R. Baghbani, M. Dehghani","doi":"10.1007/s10714-024-03266-0","DOIUrl":"https://doi.org/10.1007/s10714-024-03266-0","url":null,"abstract":"<p>For the <span>((n+1))</span>-dimensional (<span>(nge 3)</span>) dilaton black hole in the Einstein–Maxwell-dilaton theory, we have presented exact analytical solutions of the field equations. These exact solutions include the exact formula of the potential function as well as the exact formula of the metric function. The presence of the dilaton field makes the asymptotic behavior of these black holes no longer flat or anti-de Sitter. We have calculated the electric charge, mass, temperature, entropy and electric potential of these black holes and have shown the correctness of the first law of black hole thermodynamics. As a thermodynamic system, we have analyzed thermal stability of these types of black holes using the canonical ensemble method and, investigated the effect of dilaton field on their stability.</p>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141489538","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}
Pub Date : 2024-06-25DOI: 10.1007/s10714-024-03253-5
Abdelghani Errehymy, Ayan Banerjee, Orhan Donmez, Mohammed Daoud, Kottakkaran Sooppy Nisar, Abdel-Haleem Abdel-Aty
The present work looks for the possible existence of static and spherically symmetric wormhole geometries in Rastall–Rainbow gravity. Since, the Rastall–Rainbow gravity model has been constructed with the combination of Rastall theory and the gravity’s rainbow formalism. Taking advantage of the Karmarkar condition for embedding class one metrics, we solve the modified field equations analytically that describe wormholes for specific choice of redshift function. For specific parameter ranges, the solution represents a traversable wormhole that exhibits the violation of null energy condition and consequently the weak energy condition also. Furthermore, we focus on the wormhole stability via adiabatic sound velocity analysis. This model establishes a strong connection between two model parameters, namely, the Rastall parameters and the Rainbow functions, and how it affects the wormhole solution.
{"title":"Unraveling the mysteries of wormhole formation in Rastall–Rainbow gravity: a comprehensive study using the embedding approach","authors":"Abdelghani Errehymy, Ayan Banerjee, Orhan Donmez, Mohammed Daoud, Kottakkaran Sooppy Nisar, Abdel-Haleem Abdel-Aty","doi":"10.1007/s10714-024-03253-5","DOIUrl":"https://doi.org/10.1007/s10714-024-03253-5","url":null,"abstract":"<p>The present work looks for the possible existence of static and spherically symmetric wormhole geometries in Rastall–Rainbow gravity. Since, the Rastall–Rainbow gravity model has been constructed with the combination of Rastall theory and the gravity’s rainbow formalism. Taking advantage of the Karmarkar condition for embedding class one metrics, we solve the modified field equations analytically that describe wormholes for specific choice of redshift function. For specific parameter ranges, the solution represents a traversable wormhole that exhibits the violation of null energy condition and consequently the weak energy condition also. Furthermore, we focus on the wormhole stability via adiabatic sound velocity analysis. This model establishes a strong connection between two model parameters, namely, the Rastall parameters and the Rainbow functions, and how it affects the wormhole solution.</p>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141448143","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}
Pub Date : 2024-06-18DOI: 10.1007/s10714-024-03260-6
Christian G. Böhmer, Antonio d’Alfonso del Sordo
Cosmological models can be studied effectively using dynamical systems techniques. Starting from Brown’s formulation of the variational principle for relativistic fluids, we introduce new types of couplings involving a perfect fluid, a scalar field, and boundary terms. We describe three different coupling models, one of which turns out to be particularly relevant for cosmology. Its behaviour is similar to that of models in which dark matter decays into dark energy. In particular, for a constant coupling, the model mimics well-known dynamical dark energy models while the non-constant couplings offer a rich dynamical structure, unseen before. We are able to achieve this richness whilst working in a two-dimensional phase space. This is a significant advantage which allows us to provide a clear physical interpretation of the key features and draw analogies with previously studied models.
{"title":"Cosmological fluids with boundary term couplings","authors":"Christian G. Böhmer, Antonio d’Alfonso del Sordo","doi":"10.1007/s10714-024-03260-6","DOIUrl":"https://doi.org/10.1007/s10714-024-03260-6","url":null,"abstract":"<p>Cosmological models can be studied effectively using dynamical systems techniques. Starting from Brown’s formulation of the variational principle for relativistic fluids, we introduce new types of couplings involving a perfect fluid, a scalar field, and boundary terms. We describe three different coupling models, one of which turns out to be particularly relevant for cosmology. Its behaviour is similar to that of models in which dark matter decays into dark energy. In particular, for a constant coupling, the model mimics well-known dynamical dark energy models while the non-constant couplings offer a rich dynamical structure, unseen before. We are able to achieve this richness whilst working in a two-dimensional phase space. This is a significant advantage which allows us to provide a clear physical interpretation of the key features and draw analogies with previously studied models.</p>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141334289","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}
Pub Date : 2024-06-17DOI: 10.1007/s10714-024-03263-3
J. A. V. Campos, M. A. Anacleto, F. A. Brito, E. Passos
In the present work, we study the scattering for a black hole described by the canonical acoustic metric with Lorentz violation using asymptotic and numerical methods. In this scenario, we also check the effects of quasinormal modes and the acoustic shadow radius. In the eikonal limit the relationship between the shadow radius and the real part of the quasinormal frequency is preserved.
{"title":"Absorption, scattering, quasinormal modes and shadow by canonical acoustic black holes in Lorentz-violating background","authors":"J. A. V. Campos, M. A. Anacleto, F. A. Brito, E. Passos","doi":"10.1007/s10714-024-03263-3","DOIUrl":"https://doi.org/10.1007/s10714-024-03263-3","url":null,"abstract":"<p>In the present work, we study the scattering for a black hole described by the canonical acoustic metric with Lorentz violation using asymptotic and numerical methods. In this scenario, we also check the effects of quasinormal modes and the acoustic shadow radius. In the eikonal limit the relationship between the shadow radius and the real part of the quasinormal frequency is preserved.</p>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141334308","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}
Pub Date : 2024-06-14DOI: 10.1007/s10714-024-03262-4
Jorge L. deLyra
We present the solution of the Einstein field equations, in the static and spherically symmetric case, for an incompressible fluid, that has constant proper energy density at each and every point of the volume where it exists, according to a set of local observers who are stationary with respect to the fluid at each point. In the general case the fluid exists within a spherically symmetric shell with an inner vacuum-matter interface at a radial position (r_{1}) and an outer matter-vacuum interface at a radial position (r_{2}) in the Schwarzschild coordinate system. Therefore, in the general case there is an inner vacuum region with a repulsive singularity at the origin, just like in all other similar shell solutions. We present the parameter plane of the problem, and show that there are limits of solutions that approach the configuration of black holes, with the formation of an event horizon at the radial position (r_{2}).
{"title":"Complete solution of the Einstein field equations for a spherical shell of truly incompressible liquid","authors":"Jorge L. deLyra","doi":"10.1007/s10714-024-03262-4","DOIUrl":"https://doi.org/10.1007/s10714-024-03262-4","url":null,"abstract":"<p>We present the solution of the Einstein field equations, in the static and spherically symmetric case, for an incompressible fluid, that has constant <i>proper</i> energy density at each and every point of the volume where it exists, according to a set of local observers who are stationary with respect to the fluid at each point. In the general case the fluid exists within a spherically symmetric shell with an inner vacuum-matter interface at a radial position <span>(r_{1})</span> and an outer matter-vacuum interface at a radial position <span>(r_{2})</span> in the Schwarzschild coordinate system. Therefore, in the general case there is an inner vacuum region with a repulsive singularity at the origin, just like in all other similar shell solutions. We present the parameter plane of the problem, and show that there are limits of solutions that approach the configuration of black holes, with the formation of an event horizon at the radial position <span>(r_{2})</span>.</p>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141326871","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}
Pub Date : 2024-06-10DOI: 10.1007/s10714-024-03257-1
Jarmo Mäkelä
Beginning from the standard Arnowitt–Deser–Misner (ADM) formulation of general relativity we construct a tentative model of quantum gravity from the point of view of an observer with constant proper acceleration, just outside of a horizon of spacetime. In addition of producing the standard results of black-hole thermodynamics, our model makes an entirely new prediction that there is a certain upper bound for the energies of massive particles. For protons, for instance, this upper bound is around (1.1times 10^{21}) eV. The result is interesting, because this energy is roughly of the same order of magnitude as are the highest energies ever measured for protons in cosmic rays.
{"title":"A possible quantum effect of gravitation","authors":"Jarmo Mäkelä","doi":"10.1007/s10714-024-03257-1","DOIUrl":"https://doi.org/10.1007/s10714-024-03257-1","url":null,"abstract":"<p>Beginning from the standard Arnowitt–Deser–Misner (ADM) formulation of general relativity we construct a tentative model of quantum gravity from the point of view of an observer with constant proper acceleration, just outside of a horizon of spacetime. In addition of producing the standard results of black-hole thermodynamics, our model makes an entirely new prediction that there is a certain upper bound for the energies of massive particles. For protons, for instance, this upper bound is around <span>(1.1times 10^{21})</span> eV. The result is interesting, because this energy is roughly of the same order of magnitude as are the highest energies ever measured for protons in cosmic rays.\u0000</p>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141304564","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}
Pub Date : 2024-06-08DOI: 10.1007/s10714-024-03258-0
J. Klusoň
In this short note we investigate canonical formalism for General Relativity which is formulated with the metric (f^{ab}=(-g)^alpha g^{ab}). We find corresponding Hamiltonian and we show that constraint structure is the same as in the standard formulation. We also analyze another model when the spatial part of metric (h^{ij}) is related with the new one by relation (a^{ij}=(det h_{ij})^beta h^{ij}) and we argue that it corresponds to the gauge fixed version of the General Relativity formulated with the metric (f^{ab}=(-g)^alpha g^{ab}).
{"title":"Canonial analysis of general relativity formulated with the new metric $$f^{ab}=(-g)^{alpha }g^{ab}$$","authors":"J. Klusoň","doi":"10.1007/s10714-024-03258-0","DOIUrl":"https://doi.org/10.1007/s10714-024-03258-0","url":null,"abstract":"<p>In this short note we investigate canonical formalism for General Relativity which is formulated with the metric <span>(f^{ab}=(-g)^alpha g^{ab})</span>. We find corresponding Hamiltonian and we show that constraint structure is the same as in the standard formulation. We also analyze another model when the spatial part of metric <span>(h^{ij})</span> is related with the new one by relation <span>(a^{ij}=(det h_{ij})^beta h^{ij})</span> and we argue that it corresponds to the gauge fixed version of the General Relativity formulated with the metric <span>(f^{ab}=(-g)^alpha g^{ab})</span>.</p>","PeriodicalId":578,"journal":{"name":"General Relativity and Gravitation","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141292678","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}