Pub Date : 2024-07-10DOI: 10.1088/1361-6382/ad5c35
N Voicu and S G Elgendi
For a torsion-free affine connection on a given manifold, which does not necessarily arise as the Levi–Civita connection of any pseudo-Riemannian metric, it is still possible that it corresponds in a canonical way to a Finsler structure; this property is known as Finsler (or Berwald–Finsler) metrizability. In the present paper, we clarify, for four-dimensional SO(3)-invariant, Berwald–Finsler metrizable connections, the issue of the existence of an affinely equivalent pseudo-Riemannian structure. In particular, we find all classes of -invariant connections which are not Levi–Civita connections for any pseudo-Riemannian metric—hence, are non-metric in a conventional way—but can still be metrized by SO(3)-invariant Finsler functions. The implications for physics, together with some examples are briefly discussed.
{"title":"Metrizability of SO(3) -invariant connections: Riemann versus Finsler","authors":"N Voicu and S G Elgendi","doi":"10.1088/1361-6382/ad5c35","DOIUrl":"https://doi.org/10.1088/1361-6382/ad5c35","url":null,"abstract":"For a torsion-free affine connection on a given manifold, which does not necessarily arise as the Levi–Civita connection of any pseudo-Riemannian metric, it is still possible that it corresponds in a canonical way to a Finsler structure; this property is known as Finsler (or Berwald–Finsler) metrizability. In the present paper, we clarify, for four-dimensional SO(3)-invariant, Berwald–Finsler metrizable connections, the issue of the existence of an affinely equivalent pseudo-Riemannian structure. In particular, we find all classes of -invariant connections which are not Levi–Civita connections for any pseudo-Riemannian metric—hence, are non-metric in a conventional way—but can still be metrized by SO(3)-invariant Finsler functions. The implications for physics, together with some examples are briefly discussed.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141584217","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 : 2024-07-09DOI: 10.1088/1361-6382/ad5c34
Ana Bokulić, Tajron Jurić and Ivica Smolić
In classical Maxwell’s electromagnetism, the monopole term of the electric field is proportional to r−2, while higher order multipole terms, sourced by anisotropic sources, fall-off faster. However, in nonlinear electromagnetism even a spherically symmetric field has multipole-like contributions. We prove that the leading subdominant term of the electric field, defined by nonlinear electromagnetic Lagrangian obeying Maxwellian weak field limit, in a static, spherically symmetric, asymptotically flat spacetime, is of the order as . Moreover, using Lagrange inversion theorem and Faà di Bruno’s formula, we derive the series expansion of the electric field from the Taylor series of an analytic electromagnetic Lagrangian.
在经典麦克斯韦电磁学中，电场的单极子项与 r-2 成正比，而由各向异性源产生的高阶多极子项衰减得更快。然而，在非线性电磁学中，即使是球形对称场也有类似多极子的贡献。我们证明，在一个静态、球面对称、渐近平坦的时空中，由服从麦克斯韦弱场极限的非线性电磁拉格朗日定义的电场前导次主导项的数量级为 。此外，我们还利用拉格朗日反转定理和 Faà di Bruno 公式，从解析电磁拉格朗日的泰勒级数推导出电场的级数展开。
{"title":"Hexadecapole at the heart of nonlinear electromagnetic fields","authors":"Ana Bokulić, Tajron Jurić and Ivica Smolić","doi":"10.1088/1361-6382/ad5c34","DOIUrl":"https://doi.org/10.1088/1361-6382/ad5c34","url":null,"abstract":"In classical Maxwell’s electromagnetism, the monopole term of the electric field is proportional to r−2, while higher order multipole terms, sourced by anisotropic sources, fall-off faster. However, in nonlinear electromagnetism even a spherically symmetric field has multipole-like contributions. We prove that the leading subdominant term of the electric field, defined by nonlinear electromagnetic Lagrangian obeying Maxwellian weak field limit, in a static, spherically symmetric, asymptotically flat spacetime, is of the order as . Moreover, using Lagrange inversion theorem and Faà di Bruno’s formula, we derive the series expansion of the electric field from the Taylor series of an analytic electromagnetic Lagrangian.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141565987","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 : 2024-07-08DOI: 10.1088/1361-6382/ad52e3
Sam R Dolan, Leanne Durkan, Chris Kavanagh and Barry Wardell
We construct the metric perturbation in Lorenz gauge for a compact body on a circular equatorial orbit of a rotating black hole (Kerr) spacetime, using a newly-developed method of separation of variables. The metric perturbation is formed from a linear sum of differential operators acting on Teukolsky mode functions, and certain auxiliary scalars, which are solutions to ordinary differential equations in the frequency domain. For radiative modes, the solution is uniquely determined by the Weyl scalars, the s = 0 trace, and gauge scalars whose amplitudes are determined by imposing continuity conditions on the metric perturbation at the orbital radius. The static (zero-frequency) part of the metric perturbation, which is handled separately, also includes mass and angular momentum completion pieces. The metric perturbation is validated against the independent results of a 2+1D time domain code, and we demonstrate agreement at the expected level in all components, and the absence of gauge discontinuities. In principle, the new method can be used to determine the Lorenz-gauge metric perturbation at a sufficiently high precision to enable accurate second-order self-force calculations on Kerr spacetime in future. We conclude with a discussion of extensions of the method to eccentric and non-equatorial orbits.
{"title":"Metric perturbations of Kerr spacetime in Lorenz gauge: circular equatorial orbits","authors":"Sam R Dolan, Leanne Durkan, Chris Kavanagh and Barry Wardell","doi":"10.1088/1361-6382/ad52e3","DOIUrl":"https://doi.org/10.1088/1361-6382/ad52e3","url":null,"abstract":"We construct the metric perturbation in Lorenz gauge for a compact body on a circular equatorial orbit of a rotating black hole (Kerr) spacetime, using a newly-developed method of separation of variables. The metric perturbation is formed from a linear sum of differential operators acting on Teukolsky mode functions, and certain auxiliary scalars, which are solutions to ordinary differential equations in the frequency domain. For radiative modes, the solution is uniquely determined by the Weyl scalars, the s = 0 trace, and gauge scalars whose amplitudes are determined by imposing continuity conditions on the metric perturbation at the orbital radius. The static (zero-frequency) part of the metric perturbation, which is handled separately, also includes mass and angular momentum completion pieces. The metric perturbation is validated against the independent results of a 2+1D time domain code, and we demonstrate agreement at the expected level in all components, and the absence of gauge discontinuities. In principle, the new method can be used to determine the Lorenz-gauge metric perturbation at a sufficiently high precision to enable accurate second-order self-force calculations on Kerr spacetime in future. We conclude with a discussion of extensions of the method to eccentric and non-equatorial orbits.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141561360","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 : 2024-07-08DOI: 10.1088/1361-6382/ad5cbc
L Marsot
In this article, we consider some Carrollian dynamical systems as effective models on null hypersurfaces in a Lorentzian spacetime. We show that we can realize Carroll models from more usual ‘relativistic’ theories. In particular, we show how ambient null geodesics imply the classical ʼno Carroll motion’ and, more interestingly, we find that the ambient model of chiral fermions implies Hall motion on null hypersurfaces, in agreement with previous intrinsic Carroll results. We also show how Wigner–Souriau translations imply (apparent) Carroll motion, and how ambient particles with a non vanishing gyromagnetic ratio cannot have a Carrollian description.
{"title":"Induced motions on Carroll geometries","authors":"L Marsot","doi":"10.1088/1361-6382/ad5cbc","DOIUrl":"https://doi.org/10.1088/1361-6382/ad5cbc","url":null,"abstract":"In this article, we consider some Carrollian dynamical systems as effective models on null hypersurfaces in a Lorentzian spacetime. We show that we can realize Carroll models from more usual ‘relativistic’ theories. In particular, we show how ambient null geodesics imply the classical ʼno Carroll motion’ and, more interestingly, we find that the ambient model of chiral fermions implies Hall motion on null hypersurfaces, in agreement with previous intrinsic Carroll results. We also show how Wigner–Souriau translations imply (apparent) Carroll motion, and how ambient particles with a non vanishing gyromagnetic ratio cannot have a Carrollian description.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141561361","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 : 2024-07-07DOI: 10.1088/1361-6382/ad5bb7
Tingqi Cai and Yi Wang
We present a toy metric of spacetime travel from topological change. A bubble-like baby Universe is detached and re-attached from our Universe. Depending on where the bubble is re-attached, matter may travel superluminally or backwards-in-time through the bubble. Quasiregular singularities are formed at the detachment and re-attachment spacetime points. The spacetime is traversable and not covered by any horizons. Exotic matter violating energy conditions is required to realize such spacetimes.
{"title":"A topological drive for spacetime travel","authors":"Tingqi Cai and Yi Wang","doi":"10.1088/1361-6382/ad5bb7","DOIUrl":"https://doi.org/10.1088/1361-6382/ad5bb7","url":null,"abstract":"We present a toy metric of spacetime travel from topological change. A bubble-like baby Universe is detached and re-attached from our Universe. Depending on where the bubble is re-attached, matter may travel superluminally or backwards-in-time through the bubble. Quasiregular singularities are formed at the detachment and re-attachment spacetime points. The spacetime is traversable and not covered by any horizons. Exotic matter violating energy conditions is required to realize such spacetimes.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141556970","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 : 2024-07-07DOI: 10.1088/1361-6382/ad5825
M D C Torri and L Miramonti
In this paper, we aim to explore the interplay between neutrinos and quantum gravity, illustrating some proposals about the use of these particles as probes for the supposed quantized structure of spacetime. The residual signatures of a more fundamental theory of quantum gravity can manifest themselves modifying the free particle dispersion relations and the connected velocity. In neutrino sector these supposed effects can modify the time of flight for astrophysical particles with different energies and can affect the usual neutrino oscillation pattern introducing species depending perturbations. We will highlight how perturbations caused by non-standard interactions in the solar neutrino sector can mimic the presumed quantum gravity effects. In fact, the mathematical formulation of non-standard interactions is equivalent to that of CPT-odd perturbations. We will, therefore, emphasize the need to identify the nature of different contributions in order to disentangle them in the search for quantum gravity effects. As a final point we will discuss the possibility to detect in the neutrino sector decoherence effects caused by the quantum gravity supposed perturbations. By reviewing current experimental constraints and observations, we seek to shed light on the intricate relationship between neutrinos and quantum gravity, and discuss the challenges and future directions in this fascinating field of research.
{"title":"Neutrinos as possible probes for quantum gravity","authors":"M D C Torri and L Miramonti","doi":"10.1088/1361-6382/ad5825","DOIUrl":"https://doi.org/10.1088/1361-6382/ad5825","url":null,"abstract":"In this paper, we aim to explore the interplay between neutrinos and quantum gravity, illustrating some proposals about the use of these particles as probes for the supposed quantized structure of spacetime. The residual signatures of a more fundamental theory of quantum gravity can manifest themselves modifying the free particle dispersion relations and the connected velocity. In neutrino sector these supposed effects can modify the time of flight for astrophysical particles with different energies and can affect the usual neutrino oscillation pattern introducing species depending perturbations. We will highlight how perturbations caused by non-standard interactions in the solar neutrino sector can mimic the presumed quantum gravity effects. In fact, the mathematical formulation of non-standard interactions is equivalent to that of CPT-odd perturbations. We will, therefore, emphasize the need to identify the nature of different contributions in order to disentangle them in the search for quantum gravity effects. As a final point we will discuss the possibility to detect in the neutrino sector decoherence effects caused by the quantum gravity supposed perturbations. By reviewing current experimental constraints and observations, we seek to shed light on the intricate relationship between neutrinos and quantum gravity, and discuss the challenges and future directions in this fascinating field of research.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141556967","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 : 2024-07-07DOI: 10.1088/1361-6382/ad5bb4
Evgenii Ievlev
Moving mirrors have been used for a long time as simple models for studying various properties of black hole radiation, such as the thermal spectrum and entanglement entropy. These models are typically constructed to mimic the collapse of a spherically symmetric distribution of matter in the Minkowski background. We generalize this correspondence to the case of non-trivial background geometry and consider two examples, the Schwarzschild—de Sitter black hole and the Bañados–Teitelboim–Zanelli (BTZ) black hole. In the BTZ case we were also able to show that this approach works for the spinning black hole which has only axial symmetry.
{"title":"Moving mirrors and event horizons in non-flat background geometry","authors":"Evgenii Ievlev","doi":"10.1088/1361-6382/ad5bb4","DOIUrl":"https://doi.org/10.1088/1361-6382/ad5bb4","url":null,"abstract":"Moving mirrors have been used for a long time as simple models for studying various properties of black hole radiation, such as the thermal spectrum and entanglement entropy. These models are typically constructed to mimic the collapse of a spherically symmetric distribution of matter in the Minkowski background. We generalize this correspondence to the case of non-trivial background geometry and consider two examples, the Schwarzschild—de Sitter black hole and the Bañados–Teitelboim–Zanelli (BTZ) black hole. In the BTZ case we were also able to show that this approach works for the spinning black hole which has only axial symmetry.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141556969","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 : 2024-07-07DOI: 10.1088/1361-6382/ad563b
Leo C Stein
In this short Note, I answer the titular question: yes, a radiation gauge can be horizon-locking. Radiation gauges are very common in black hole perturbation theory. It’s also very convenient if a gauge choice is horizon-locking, i.e. the location of the horizon is not moved by a linear metric perturbation. Therefore it is doubly convenient that a radiation gauge can be horizon-locking, when some simple criteria are satisfied. Though the calculation is straightforward, it seemed useful enough to warrant writing this Note. Finally I show an example: the vector of the Hartle–Hawking tetrad in Kerr satisfies all the conditions for ingoing radiation gauge to keep the future horizon fixed.
{"title":"Can a radiation gauge be horizon-locking?","authors":"Leo C Stein","doi":"10.1088/1361-6382/ad563b","DOIUrl":"https://doi.org/10.1088/1361-6382/ad563b","url":null,"abstract":"In this short Note, I answer the titular question: yes, a radiation gauge can be horizon-locking. Radiation gauges are very common in black hole perturbation theory. It’s also very convenient if a gauge choice is horizon-locking, i.e. the location of the horizon is not moved by a linear metric perturbation. Therefore it is doubly convenient that a radiation gauge can be horizon-locking, when some simple criteria are satisfied. Though the calculation is straightforward, it seemed useful enough to warrant writing this Note. Finally I show an example: the vector of the Hartle–Hawking tetrad in Kerr satisfies all the conditions for ingoing radiation gauge to keep the future horizon fixed.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141556968","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 : 2024-07-04DOI: 10.1088/1361-6382/ad5c33
Alan Barnes
Recently Harada proposed a third-order gravitational theory for the derivatives of the metric. Mantica and Molinari showed that Harada’s theory may be recast into the form of Einstein’s field equations (EFEs) with an additional source term which is a second-order conformal Killing tensor. Accordingly they named the theory conformal Killing gravity. However, they overlooked the fact that all solutions of the new theory (except those satisfying EFEs) admit a non-trivial second-order Killing tensor. Harada derived an analog of the Schwarzschild solution. Recently Tarciso et al obtained a generalization of Harada’s vacuum solution analogous to the Reissner–Nordström solution. However, like Harada they assumed a restricted form for a static spherically symmetric metric. In this study the most general spherically symmetric static vacuum solution of Harada’s theory and its generalization with a Maxwell electromagnetic field as source were obtained. The validity of Birkhoff’s theorem for static spherically symmetric electrovac fields in conformal Killing gravity is investigated.
{"title":"Spherically symmetric electrovac spacetimes in conformal Killing gravity","authors":"Alan Barnes","doi":"10.1088/1361-6382/ad5c33","DOIUrl":"https://doi.org/10.1088/1361-6382/ad5c33","url":null,"abstract":"Recently Harada proposed a third-order gravitational theory for the derivatives of the metric. Mantica and Molinari showed that Harada’s theory may be recast into the form of Einstein’s field equations (EFEs) with an additional source term which is a second-order conformal Killing tensor. Accordingly they named the theory conformal Killing gravity. However, they overlooked the fact that all solutions of the new theory (except those satisfying EFEs) admit a non-trivial second-order Killing tensor. Harada derived an analog of the Schwarzschild solution. Recently Tarciso et al obtained a generalization of Harada’s vacuum solution analogous to the Reissner–Nordström solution. However, like Harada they assumed a restricted form for a static spherically symmetric metric. In this study the most general spherically symmetric static vacuum solution of Harada’s theory and its generalization with a Maxwell electromagnetic field as source were obtained. The validity of Birkhoff’s theorem for static spherically symmetric electrovac fields in conformal Killing gravity is investigated.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141545768","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 : 2024-07-03DOI: 10.1088/1361-6382/ad5826
Geoffrey Compère, Sk Jahanur Hoque and Emine Şeyma Kutluk
We obtain the closed form expression for the metric perturbation around de Sitter spacetime generated by a matter source below Hubble scale both in generalized harmonic gauge and in Bondi gauge up to quadrupolar order in the multipolar expansion, including both parities (i.e. both mass and current quadrupoles). We demonstrate that such a source causes a displacement memory effect close to future infinity that originates, in the even-parity sector, from a Λ-BMS transition between the two non-radiative regions of future infinity.
{"title":"Quadrupolar radiation in de Sitter: displacement memory and Bondi metric","authors":"Geoffrey Compère, Sk Jahanur Hoque and Emine Şeyma Kutluk","doi":"10.1088/1361-6382/ad5826","DOIUrl":"https://doi.org/10.1088/1361-6382/ad5826","url":null,"abstract":"We obtain the closed form expression for the metric perturbation around de Sitter spacetime generated by a matter source below Hubble scale both in generalized harmonic gauge and in Bondi gauge up to quadrupolar order in the multipolar expansion, including both parities (i.e. both mass and current quadrupoles). We demonstrate that such a source causes a displacement memory effect close to future infinity that originates, in the even-parity sector, from a Λ-BMS transition between the two non-radiative regions of future infinity.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141521463","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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