Pub Date : 2024-08-19DOI: 10.1088/1361-6382/ad41b1
Thorsten Lang and Susanne Schander
In this series of papers, we present a set of methods to revive quantum geometrodynamics which encountered numerous mathematical and conceptual challenges in its original form promoted by Wheeler and De Witt. In this paper, we introduce the regularization scheme on which we base the subsequent quantization and continuum limit of the theory. Specifically, we employ the set of piecewise constant fields as the phase space of classical geometrodynamics, resulting in a theory with finitely many degrees of freedom of the spatial metric field. As this representation effectively corresponds to a lattice theory, we can utilize well-known techniques to depict the constraints and their algebra on the lattice. We are able to compute the lattice corrections to the constraint algebra. This model can now be quantized using the usual methods of finite-dimensional quantum mechanics, as we demonstrate in the following paper. The application of the continuum limit is the subject of a future publication.
{"title":"Quantum geometrodynamics revived I. Classical constraint algebra","authors":"Thorsten Lang and Susanne Schander","doi":"10.1088/1361-6382/ad41b1","DOIUrl":"https://doi.org/10.1088/1361-6382/ad41b1","url":null,"abstract":"In this series of papers, we present a set of methods to revive quantum geometrodynamics which encountered numerous mathematical and conceptual challenges in its original form promoted by Wheeler and De Witt. In this paper, we introduce the regularization scheme on which we base the subsequent quantization and continuum limit of the theory. Specifically, we employ the set of piecewise constant fields as the phase space of classical geometrodynamics, resulting in a theory with finitely many degrees of freedom of the spatial metric field. As this representation effectively corresponds to a lattice theory, we can utilize well-known techniques to depict the constraints and their algebra on the lattice. We are able to compute the lattice corrections to the constraint algebra. This model can now be quantized using the usual methods of finite-dimensional quantum mechanics, as we demonstrate in the following paper. The application of the continuum limit is the subject of a future publication.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142007325","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 : 2024-08-19DOI: 10.1088/1361-6382/ad6c9d
Jialu Chang, Qiyue Wu, Zhiyuan Wang, Jingxuan Zhang, Qiang Wei, Wenhao Yuan, Deyuan Zhu, Jiarui Zhang, Xuying Li, Xinpeng Wu, Zehuang Lu and Jie Zhang
Ultra-stable lasers are pivotal in various scientific applications, notably in space gravitational wave detection projects. We develop a space-borne ultra-stable laser system based on a home-made non-planar ring oscillator (NPRO) laser and an ultra-stable cavity laser stabilization system. The ultra-stable cavity is a vertically mounted 8 cm long cavity, with tunable zero-crossing temperature and low vibrational sensitivity. To make a cavity with any standard grade ultra-low expansion glass (ULE) material, and tune the zero-crossing temperature to the satellite platform temperature, we design three ultra-stable cavities with different configurations to unambiguously explore their thermal properties. The measurement results meet the design goals well, and the zero-crossing temperature of the cavity can be tuned from C to 16.0 °C. We measure the temperature fluctuation noise through modulation experiment, and it agrees well with the theoretical simulations. The vibrational sensitivities in three directions are measured to be around 10−11 /g–10−10 /g. The total weight of the system is 14.0 kg, with a volume of about 18 L, and the power dissipation of the electrical system is 18.6 W. Finally, the prototype of the space-borne laser shows a frequency instability of 9.5 at 0.2 s, and the frequency noise is measured to be 3.6 Hz/Hz1/2 at 6 mHz over three months, satisfying the mission targets of all current space gravitational wave detection programs.
{"title":"A space-borne ultra-stable laser system with an excellent long-term frequency stability for gravitational wave detection","authors":"Jialu Chang, Qiyue Wu, Zhiyuan Wang, Jingxuan Zhang, Qiang Wei, Wenhao Yuan, Deyuan Zhu, Jiarui Zhang, Xuying Li, Xinpeng Wu, Zehuang Lu and Jie Zhang","doi":"10.1088/1361-6382/ad6c9d","DOIUrl":"https://doi.org/10.1088/1361-6382/ad6c9d","url":null,"abstract":"Ultra-stable lasers are pivotal in various scientific applications, notably in space gravitational wave detection projects. We develop a space-borne ultra-stable laser system based on a home-made non-planar ring oscillator (NPRO) laser and an ultra-stable cavity laser stabilization system. The ultra-stable cavity is a vertically mounted 8 cm long cavity, with tunable zero-crossing temperature and low vibrational sensitivity. To make a cavity with any standard grade ultra-low expansion glass (ULE) material, and tune the zero-crossing temperature to the satellite platform temperature, we design three ultra-stable cavities with different configurations to unambiguously explore their thermal properties. The measurement results meet the design goals well, and the zero-crossing temperature of the cavity can be tuned from C to 16.0 °C. We measure the temperature fluctuation noise through modulation experiment, and it agrees well with the theoretical simulations. The vibrational sensitivities in three directions are measured to be around 10−11 /g–10−10 /g. The total weight of the system is 14.0 kg, with a volume of about 18 L, and the power dissipation of the electrical system is 18.6 W. Finally, the prototype of the space-borne laser shows a frequency instability of 9.5 at 0.2 s, and the frequency noise is measured to be 3.6 Hz/Hz1/2 at 6 mHz over three months, satisfying the mission targets of all current space gravitational wave detection programs.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142007328","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 : 2024-08-19DOI: 10.1088/1361-6382/ad6be0
Stefano Vignolo, Fabrizio Esposito and Sante Carloni
Using the notion of distribution-valued tensor, we discuss the junction conditions within the framework of -gravity. We obtain the necessary and sufficient conditions for two distinct solutions of the field equations to be smoothly joined on a given separation hypersurface.
{"title":"A note on the junction conditions in f ( Q ...","authors":"Stefano Vignolo, Fabrizio Esposito and Sante Carloni","doi":"10.1088/1361-6382/ad6be0","DOIUrl":"https://doi.org/10.1088/1361-6382/ad6be0","url":null,"abstract":"Using the notion of distribution-valued tensor, we discuss the junction conditions within the framework of -gravity. We obtain the necessary and sufficient conditions for two distinct solutions of the field equations to be smoothly joined on a given separation hypersurface.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142007326","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 : 2024-08-13DOI: 10.1088/1361-6382/ad5cbb
Aldo Riello and Laurent Freidel
In this paper, we provide a comprehensive study of asymptotically flat spacetime in even dimensions . We analyze the most general boundary condition and asymptotic symmetry compatible with Penrose’s definition of asymptotic null infinity through conformal compactification. Following Penrose’s prescription and using a minimal version of the Bondi–Sachs gauge, we show that is naturally equipped with a Carrollian stress tensor whose radial derivative defines the asymptotic Weyl tensor. This analysis describes asymptotic infinity as a stretched horizon in the conformally compactified spacetime. We establish that charge aspects conservation can be written as Carrollian Bianchi identities for the asymptotic Weyl tensor. We then provide a covariant renormalization for the asymptotic symplectic potential, which results in a finite symplectic flux and asymptotic charges. The renormalization scheme works even in the presence of logarithmic anomalies.
{"title":"Renormalization of conformal infinity as a stretched horizon","authors":"Aldo Riello and Laurent Freidel","doi":"10.1088/1361-6382/ad5cbb","DOIUrl":"https://doi.org/10.1088/1361-6382/ad5cbb","url":null,"abstract":"In this paper, we provide a comprehensive study of asymptotically flat spacetime in even dimensions . We analyze the most general boundary condition and asymptotic symmetry compatible with Penrose’s definition of asymptotic null infinity through conformal compactification. Following Penrose’s prescription and using a minimal version of the Bondi–Sachs gauge, we show that is naturally equipped with a Carrollian stress tensor whose radial derivative defines the asymptotic Weyl tensor. This analysis describes asymptotic infinity as a stretched horizon in the conformally compactified spacetime. We establish that charge aspects conservation can be written as Carrollian Bianchi identities for the asymptotic Weyl tensor. We then provide a covariant renormalization for the asymptotic symplectic potential, which results in a finite symplectic flux and asymptotic charges. The renormalization scheme works even in the presence of logarithmic anomalies.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141980976","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 : 2024-08-13DOI: 10.1088/1361-6382/ad694e
Yassine Sekhmani, Dhruba Jyoti Gogoi, Ratbay Myrzakulov, Giuseppe Gaetano Luciano and Javlon Rayimbaev
In this work, we examine the optical behaviors and thermodynamic phase structures using shadow analysis for four black holes. The study is conducted for four cases of charge configurations on the parameter space . As a matter of fact, both the electric charge as a parameter and the parameter space affect the geometry of the black hole shadow, particularly the size of the shadow. We also introduce a constraint on the charge of the black hole from the observational results of the M87 and Sgr A shadow. Furthermore, we show that the electric charge and the parameter space have a non-trivial impact on the variation of the energy emission rate. Interestingly enough, we find novel scenarios in which the evaporation is slower, which causes the lifetime of the black holes to be considerably elongated. On the other side, the phase structure of four black holes is explored for two cases of electric charge configuration. The findings show a perfect correlation between the shadow and event horizon radii. This correlation is, in fact, helpful in discovering the phase transition in terms of the shadow radius. In addition, the microstructure is being analyzed in terms of shadow analysis, providing similar behavior to the ordinary situation of the Ruppeiner formalism.
在这项研究中，我们利用阴影分析法研究了四个黑洞的光学行为和热力学相结构。研究针对参数空间上的四种电荷配置情况。事实上，作为参数的电荷和参数空间都会影响黑洞阴影的几何形状，尤其是阴影的大小。我们还从 M87 和 Sgr A 黑洞阴影的观测结果中引入了对黑洞电荷的约束。此外，我们还表明电荷和参数空间对能量发射率的变化有非同小可的影响。有趣的是，我们发现了一些新情况，在这些情况下，蒸发速度较慢，从而导致黑洞的寿命大大延长。另一方面，我们探索了两种电荷配置情况下四个黑洞的相结构。研究结果表明，阴影和事件视界半径之间存在完美的相关性。事实上，这种相关性有助于发现阴影半径的相变。此外，用阴影分析法分析了微观结构，其行为与鲁普伊纳形式主义的普通情况类似。
{"title":"Four S T ...","authors":"Yassine Sekhmani, Dhruba Jyoti Gogoi, Ratbay Myrzakulov, Giuseppe Gaetano Luciano and Javlon Rayimbaev","doi":"10.1088/1361-6382/ad694e","DOIUrl":"https://doi.org/10.1088/1361-6382/ad694e","url":null,"abstract":"In this work, we examine the optical behaviors and thermodynamic phase structures using shadow analysis for four black holes. The study is conducted for four cases of charge configurations on the parameter space . As a matter of fact, both the electric charge as a parameter and the parameter space affect the geometry of the black hole shadow, particularly the size of the shadow. We also introduce a constraint on the charge of the black hole from the observational results of the M87 and Sgr A shadow. Furthermore, we show that the electric charge and the parameter space have a non-trivial impact on the variation of the energy emission rate. Interestingly enough, we find novel scenarios in which the evaporation is slower, which causes the lifetime of the black holes to be considerably elongated. On the other side, the phase structure of four black holes is explored for two cases of electric charge configuration. The findings show a perfect correlation between the shadow and event horizon radii. This correlation is, in fact, helpful in discovering the phase transition in terms of the shadow radius. In addition, the microstructure is being analyzed in terms of shadow analysis, providing similar behavior to the ordinary situation of the Ruppeiner formalism.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141980977","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 : 2024-08-12DOI: 10.1088/1361-6382/ad694d
E Capote, L Dartez and D Davis
The next generation of ground-based gravitational-wave interferometers is expected to generate a bounty of new astrophysical discoveries, with sensitivities and bandwidths greatly improved compared to current-generation detectors. These detectors will allow us to make exceptional advancements in our understanding of fundamental physics, the dynamics of dense matter, and the cosmic history of compact objects. The fundamental design aspects of these planned interferometers will enable these new discoveries; however, challenges in technical noise, data quality, and calibration have the potential to limit the scientific reach of these instruments. In this work, we evaluate the requirements of these elements for next-generation gravitational-wave science, focusing on how these areas may impact the proposed Cosmic Explorer observatory. We highlight multiple aspects of these fields where additional research and development is required to ensure Cosmic Explorer reaches its full potential.
{"title":"Technical noise, data quality, and calibration requirements for next-generation gravitational-wave science","authors":"E Capote, L Dartez and D Davis","doi":"10.1088/1361-6382/ad694d","DOIUrl":"https://doi.org/10.1088/1361-6382/ad694d","url":null,"abstract":"The next generation of ground-based gravitational-wave interferometers is expected to generate a bounty of new astrophysical discoveries, with sensitivities and bandwidths greatly improved compared to current-generation detectors. These detectors will allow us to make exceptional advancements in our understanding of fundamental physics, the dynamics of dense matter, and the cosmic history of compact objects. The fundamental design aspects of these planned interferometers will enable these new discoveries; however, challenges in technical noise, data quality, and calibration have the potential to limit the scientific reach of these instruments. In this work, we evaluate the requirements of these elements for next-generation gravitational-wave science, focusing on how these areas may impact the proposed Cosmic Explorer observatory. We highlight multiple aspects of these fields where additional research and development is required to ensure Cosmic Explorer reaches its full potential.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141973884","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 : 2024-08-11DOI: 10.1088/1361-6382/ad68f0
Mila Bileska, James Olsen and Igor Klebanov
This work re-derives and discusses non-Lorentz invariant variable speed of light (VSL) theories in the context of cosmological problems. Following a thorough introduction to the subject, an explicit solution demonstrating a possible dependence of the speed of light on the cosmological scale factor is presented and analyzed. The parameters of the initial ansatz, , are constrained by requiring the VSL formulation to be a solution to the flatness and horizon problems. The theoretical section is concluded with a derivation of the change of entropy in a VSL Universe. Even though such findings imply that the speed of light can vary only in non-flat spacetime, an adapted approach using the Generalized Second Law of Thermodynamics is shown to loosen this restriction. Further, in the experimental section, recent evidence for a temporally varying fine structure constant at significance is presented as a potential test for the VSL hypothesis. Overall, this work introduces and evaluates many aspects of non-Lorentz invariant VSL theories whilst encouraging future research and serving as a largely self-sufficient comprehensive overview paper.
{"title":"A review of non-Lorentz invariant variable speed of light theories","authors":"Mila Bileska, James Olsen and Igor Klebanov","doi":"10.1088/1361-6382/ad68f0","DOIUrl":"https://doi.org/10.1088/1361-6382/ad68f0","url":null,"abstract":"This work re-derives and discusses non-Lorentz invariant variable speed of light (VSL) theories in the context of cosmological problems. Following a thorough introduction to the subject, an explicit solution demonstrating a possible dependence of the speed of light on the cosmological scale factor is presented and analyzed. The parameters of the initial ansatz, , are constrained by requiring the VSL formulation to be a solution to the flatness and horizon problems. The theoretical section is concluded with a derivation of the change of entropy in a VSL Universe. Even though such findings imply that the speed of light can vary only in non-flat spacetime, an adapted approach using the Generalized Second Law of Thermodynamics is shown to loosen this restriction. Further, in the experimental section, recent evidence for a temporally varying fine structure constant at significance is presented as a potential test for the VSL hypothesis. Overall, this work introduces and evaluates many aspects of non-Lorentz invariant VSL theories whilst encouraging future research and serving as a largely self-sufficient comprehensive overview paper.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141918892","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 : 2024-08-08DOI: 10.1088/1361-6382/ad69f5
R R S Oliveira
In this paper, we determine the relativistic and nonrelativistic energy levels for Dirac fermions in a spinning conical Gödel-type spacetime in -dimensions, where we work with the curved Dirac equation in polar coordinates and we use the tetrads formalism. Solving a second-order differential equation for the two components of the Dirac spinor, we obtain a generalized Laguerre equation, and the relativistic energy levels of the fermion and antifermion, where such levels are quantized in terms of the radial and total magnetic quantum numbers n and mj, and explicitly depends on the spin parameter s (describes the ‘spin’), spinorial parameter u (describes the two components of the spinor), curvature and rotation parameters α and β (describes the conical curvature and the angular momentum of the spinning cosmic string), and on the vorticity parameter Ω (describes the Gödel-type spacetime). In particular, the quantization is a direct result of the existence of Ω (i.e. such quantity acts as a kind of ‘external field or potential’). We see that for , the energy levels do not depend on s and u; however, depend on n, mj, α, and β. In this case, α breaks the degeneracy of the energy levels and such levels can increase infinitely in the limit . Already for , we see that the energy levels depends on s, u and n; however, it no longer depends on mj, α and β. In this case, it is as if the fermion/antifermion ‘lives only in a flat Gödel-type spacetime’. Besides, we also study the low-energy or nonrelativistic limit of the system. In both cases (relativistic and nonrelativistic), we graphically analyze the behavior of energy levels as a function of Ω, α, and β for three different values of n (ground state and the first two excited states).
{"title":"Dirac fermions in a spinning conical Gödel-type spacetime","authors":"R R S Oliveira","doi":"10.1088/1361-6382/ad69f5","DOIUrl":"https://doi.org/10.1088/1361-6382/ad69f5","url":null,"abstract":"In this paper, we determine the relativistic and nonrelativistic energy levels for Dirac fermions in a spinning conical Gödel-type spacetime in -dimensions, where we work with the curved Dirac equation in polar coordinates and we use the tetrads formalism. Solving a second-order differential equation for the two components of the Dirac spinor, we obtain a generalized Laguerre equation, and the relativistic energy levels of the fermion and antifermion, where such levels are quantized in terms of the radial and total magnetic quantum numbers n and mj, and explicitly depends on the spin parameter s (describes the ‘spin’), spinorial parameter u (describes the two components of the spinor), curvature and rotation parameters α and β (describes the conical curvature and the angular momentum of the spinning cosmic string), and on the vorticity parameter Ω (describes the Gödel-type spacetime). In particular, the quantization is a direct result of the existence of Ω (i.e. such quantity acts as a kind of ‘external field or potential’). We see that for , the energy levels do not depend on s and u; however, depend on n, mj, α, and β. In this case, α breaks the degeneracy of the energy levels and such levels can increase infinitely in the limit . Already for , we see that the energy levels depends on s, u and n; however, it no longer depends on mj, α and β. In this case, it is as if the fermion/antifermion ‘lives only in a flat Gödel-type spacetime’. Besides, we also study the low-energy or nonrelativistic limit of the system. In both cases (relativistic and nonrelativistic), we graphically analyze the behavior of energy levels as a function of Ω, α, and β for three different values of n (ground state and the first two excited states).","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141908942","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 : 2024-08-07DOI: 10.1088/1361-6382/ad6740
Denis Werth, Lucas Pinol and Sébastien Renaux-Petel
Cosmological correlators hold the key to high-energy physics as they probe the earliest moments of our Universe, and conceal hidden mathematical structures. However, even at tree-level, perturbative calculations are limited by technical difficulties absent in flatspace Feynman diagrammatics. In this paper, we introduce CosmoFlow: a new accurate open source Python code that computes tree-level cosmological correlators by tracing their time flow. This code is specifically designed to offer a simple, intuitive and flexible coding environment to theorists, primordial and late-time cosmologists. It can typically serve to complement analytical computations, to provide physical intuition when studying various inflationary theories, and to obtain exact results in regimes that are analytically out of reach. This paper presents the basic structure of CosmoFlow, leads the reader through an in-depth user-guide, and illustrates how it can be used with a series of worked examples. Our hope is that this first building block sets the stage for a bank of theoretical data, which can be nurtured and enhanced collaboratively by the community. CosmoFlow is publicly available on GitHub.
{"title":"C ...","authors":"Denis Werth, Lucas Pinol and Sébastien Renaux-Petel","doi":"10.1088/1361-6382/ad6740","DOIUrl":"https://doi.org/10.1088/1361-6382/ad6740","url":null,"abstract":"Cosmological correlators hold the key to high-energy physics as they probe the earliest moments of our Universe, and conceal hidden mathematical structures. However, even at tree-level, perturbative calculations are limited by technical difficulties absent in flatspace Feynman diagrammatics. In this paper, we introduce CosmoFlow: a new accurate open source Python code that computes tree-level cosmological correlators by tracing their time flow. This code is specifically designed to offer a simple, intuitive and flexible coding environment to theorists, primordial and late-time cosmologists. It can typically serve to complement analytical computations, to provide physical intuition when studying various inflationary theories, and to obtain exact results in regimes that are analytically out of reach. This paper presents the basic structure of CosmoFlow, leads the reader through an in-depth user-guide, and illustrates how it can be used with a series of worked examples. Our hope is that this first building block sets the stage for a bank of theoretical data, which can be nurtured and enhanced collaboratively by the community. CosmoFlow is publicly available on GitHub.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141904523","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 : 2024-08-07DOI: 10.1088/1361-6382/ad672d
J Struckmeier, D Vasak, A Redelbach and H Stöcker
In this study we prove that the Pauli interaction—which is associated with a length parameter—emerges when the minimal coupling recipe is applied to the non-degenerate version of the Dirac Lagrangian. The conventional Dirac Lagrangian is rendered non-degenerate if supplemented by a particular term quadratic in the derivatives of the spinors. For dimensional reasons, this non-degenerate Dirac Lagrangian is associated with a length parameter . It yields the standard free Dirac equation in Minkowski space. However, if the Dirac spinor is minimally coupled to gauge fields, then the length parameter becomes a physical coupling constant yielding novel interactions. For the U(1) symmetry the Pauli coupling of fermions to electromagnetic fields arises, modifying the fermion’s magnetic moment. We discuss the impact of these findings on electrodynamics, and estimate the upper bound of the length parameter from the yet existing discrepancy between the (SM) theory and measurement of the anomalous magnetic moment of light leptons. This, and also recent studies of the renormalization theory, suggest that the Pauli coupling of leptons to the electromagnetic field is a necessary ingredient in quantum electrodynamics (QED), supporting the notion of a fundamental nature of the non-degenerate Dirac Lagrangian. In a second step we then investigate how analogous ‘Pauli-type’ couplings of gravity and matter arise if fermions are embedded in curved spacetime. Minimal coupling of the Dirac field to the gauge field of gravity, the spin connection, leads to an anomalous spin-torsion interaction and a curvature-dependent mass correction. The relation of the latter to Mach’s Principle is discussed. Moreover, it is found for a totally anti-symmetric torsion that an upper limit for the ‘strength’ of the torsion exists in order for a solution to remain causal, while causality for a vector torsion requires a lower limit for its amplitude. We calculate the mass correction in the De Sitter geometry of vacuum with the cosmological constant Λ. Possible implications for the existence of effective non-zero rest masses of neutrinos are addressed. Finally, an outlook on the impact of mass correction on the physics of ‘Big Bang’ cosmology, black holes, and of neutron stars is provided.
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