Article
Physics, Particles & Fields
Areef Waeming, Tanech Klangburam, Chakrit Pongkitivanichkul, Daris Samart
Summary: In this study, we investigate the Brans-Dicke model inspired by Kaluza-Klein theory and introduce additional scalar and gauge fields. The inclusion of barotropic matter in the compactification process leads to the determination of critical points that indicate the presence of dark matter, dark energy, and phantom dark energy.
EUROPEAN PHYSICAL JOURNAL C
(2022)
Article
Physics, Mathematical
Jinhua Wang
Summary: This paper proves the global existence for the Cauchy problem of a semi-linear wave equation with an arbitrary quadratic form in a cosmological Kaluza-Klein spacetime. The key to the proof lies in decomposing the wave equation into zero and non-zero modes and observing a crucial nonlinear structure after this decomposition. Various modified energies and associated energy identities are introduced based on different expectations of decaying estimates.
JOURNAL OF MATHEMATICAL PHYSICS
(2021)
Article
Physics, Multidisciplinary
Marcus A. Khuri, Jordan F. Rainone
Summary: We present the first examples of formally asymptotically flat black hole solutions with horizons of general lens space topology L(p, q). These solutions are five-dimensional static or stationary spacetimes that are regular on and outside the event horizon, and supported by Kaluza-Klein matter fields. Additionally, we obtain new examples of regular gravitational instantons in higher dimensions.
PHYSICAL REVIEW LETTERS
(2023)
Article
Astronomy & Astrophysics
Murat Korunur
Summary: In this study, a correspondence between quintessence, tachyon, and dilaton scalar field definitions and the generalized ghost dark energy model was established in a five-dimensional framework. Numerical analysis of equation of state parameters, kinetic energy, and scalar potential terms was conducted.
CLASSICAL AND QUANTUM GRAVITY
(2021)
Article
Astronomy & Astrophysics
Shulei Cao, Bharat Ratra
Summary: This study uses a combination of cosmological data to constrain cosmological parameters in six different models. The results provide model-independent determinations of the Hubble constant and the current non-relativistic matter density parameter. The error bars in these determinations are larger than those in the flat Lambda CDM model, but mild dark energy dynamics and a little spatial curvature are not ruled out.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Shinya Tomizawa, Takahisa Igata
Summary: Stable circular orbits are found around squashed and multi-Kaluza-Klein black holes, with the radius of the innermost stable circular orbit monotonically depending on the size of an extra dimension for a single black hole, and also depending on the separation between two black holes for two black holes. The potential's stationary points form two branches, with stable circular orbits existing on both branches for large separations regardless of extra dimension size, and only on one branch for small separations, where the innermost stable circular orbit radius increases monotonically with extra dimension size.
Article
Astronomy & Astrophysics
Jean-Luc Lehners
Summary: Recently, there have been discussions on permissible complex metrics in quantum gravity, assuming real-valued matter fields. It has been observed that demanding convergence of the theory's path integral in the higher-dimensional parent theory makes sense for compactified solutions. This allows for more general matter configurations, including complex scalar fields with a bound on their imaginary parts.
Article
Astronomy & Astrophysics
Giovanni Montani, Sebastiano Segreto
Summary: The reanalysis of the 5D Kaluza-Klein theory with the implementation of polymer representation in both classical and quantum levels provides valuable insights into the existence of a cut off scale and introduces a new solution in the context of semiclassical quantum mechanics. This revised formulation overcomes puzzling questions of the standard model and allows for the attribution of charge to mass ratio to particles predicted by the Standard Model. However, a problem with the charge to mass ratio still persists in the quantum field formulation.
Article
Astronomy & Astrophysics
Narayan Khadka, Bharat Ratra
Summary: The study found that the parameters of the X-ray and UV luminosities relation for the full QSO data set depend on the cosmological model used. Subset of QSO data with lower redshifts show a relationship between X-ray and UV flux independent of cosmological model, which can be used to constrain cosmological parameters. The cosmological constraints from these lower redshift QSO data subsets are mostly consistent with other measurements but weaker in strength.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Review
Astronomy & Astrophysics
Seyed Meraj Mousavi Rasouli, Shahram Jalalzadeh, Paulo Moniz
Summary: This article presents a brief description of noncompactified higher-dimensional theories from the perspective of general relativity. It explains the Space-Time-Matter theory and the reduction procedure used to construct modified theories. The latter is applied to the FLRW cosmological models in arbitrary dimensions and the corresponding solutions are analyzed.
Article
Astronomy & Astrophysics
Timur Takhtaganov, Zarija Lukic, Juliane Mueller, Dmitriy Morozov
Summary: In this paper, a novel statistical framework utilizing multi-output Gaussian process emulators adaptively constructed using Bayesian optimization methods is proposed to maintain low emulation error in the region of the hypercube preferred by observational data. The approach allows for fewer simulations compared to traditional emulation methods and is more robust in reconstructing parameters and their Bayesian credible intervals, as demonstrated with a Ly alpha forest flux power spectrum.
ASTROPHYSICAL JOURNAL
(2021)
Article
Astronomy & Astrophysics
K. Dasu Naidu, Y. Aditya, R. L. Naidu, D. R. K. Reddy
Summary: The paper discusses the dynamical aspects of a Kaluza-Klein five-dimensional cosmological model with a massive scalar field and minimally interacting baryonic matter and dark energy. By obtaining a determinate solution, various parameters of the model are determined, and peculiar behaviors such as the transition of the equation of state parameter from quintessence to phantom are observed. The dynamics of cosmological parameters indicate accelerated expansion of the universe, consistent with current cosmological observations.
MODERN PHYSICS LETTERS A
(2021)
Article
Physics, Particles & Fields
Tran N. Hung, Cao H. Nam
Summary: We investigate the topological defects in the thermodynamics of regular black strings in a high-dimensional spacetime with an extra compactified dimension under the double Wick rotation symmetry. We find that the phases of regular black strings can be classified by the winding numbers, which determine their thermodynamic stability. The topological classification leads to a phase transition from a thermodynamically unstable black string to a thermodynamically stable one. By analyzing the free energy, heat capacity, and Ruppeiner scalar curvature, we verify these topological properties of regular black strings, and find that their interactions are always attractive.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Physics, Multidisciplinary
Sudipto Roy, Asmita Das, Anwesha Dey, Debolina Biswas, Sudipto Saha Roy
Summary: The present study aims to determine the characteristics of time evolution for various cosmological quantities in a universe undergoing accelerated expansion, based on four constructed models. The findings from these models are consistent with each other and in agreement with observed features. The gravitational constant shows a rapid fall in the early universe and a slow rise at the present time. The signature flip of the deceleration parameter almost coincides with the signature flip of the cosmological constant, pointing towards a relation between the accelerated expansion and the dark energy represented by the cosmological term.
EAST EUROPEAN JOURNAL OF PHYSICS
(2023)
Article
Physics, Particles & Fields
Carmen Gomez-Fayren, Patrick Meessen, Tomas Ortin, Matteo Zatti
Summary: In this study, we use Wald's formalism to investigate the thermodynamics of 4-dimensional electrically charged black-hole solutions in the simplest 5-dimensional Kaluza-Klein theory. We demonstrate how the electric work term, which is present in the 4-dimensional first law of black-hole thermodynamics, arises in the purely gravitational 5-dimensional framework. Additionally, we find an interesting geometric interpretation of the 4-dimensional electrostatic potential, similar to the angular velocity in rotating black holes. Furthermore, we show how the momentum map equation arises as a result of demanding compatibility between the timelike Killing vector of the black-hole solution and the spatial Killing vector of the 5-dimensional background.
JOURNAL OF HIGH ENERGY PHYSICS
(2023)
