Article
Astronomy & Astrophysics
Sebastian Garcia-Saenz
Summary: Our analysis shows that coupling between vector fields described by the generalized Proca class of theories and a gravitational sector defined by a scalar-tensor theory of the degenerate type leads to the loss of at least one constraint associated with the scalar-tensor sector.
Article
Physics, Particles & Fields
Jose Barrientos, Adolfo Cisterna, Cristobal Corral, Marcelo Oyarzo
Summary: The paper presents novel regular Euclidean solutions to General Relativity with Maxwell and conformally coupled scalar fields. The authors analyze the metrics of the Eguchi-Hanson and Taub-NUT families and solve the field equations analytically. The solutions have nontrivial topology and the authors compute the Euler characteristic explicitly. They also investigate the modifications to the solutions in the presence of higher-curvature corrections that respect conformal invariance.
JOURNAL OF HIGH ENERGY PHYSICS
(2022)
Article
Physics, Multidisciplinary
Taishi Ikeda, Vitor Cardoso, Miguel Zilhao
Summary: The behavior of fundamental fields in strong gravity or nontrivial environments plays a vital role in understanding nature. In this study, the dynamics of scalar fields in dynamic backgrounds were investigated, revealing implications for constraining the parameter space of scalar-tensor theories. The study sheds light on the significance of studying fundamental fields in dynamic environments.
PHYSICAL REVIEW LETTERS
(2021)
Article
Physics, Particles & Fields
Sk. Moinuddin, Pradip Mukherjee, Anirban Saha, Amit Singha Roy
Summary: Unlike minimally coupled gravity theory, non-minimally coupled theories have intertwined matter and gravity sectors, leading to the arbitrariness in calculating the energy momentum tensor. In this paper, we propose an algorithm based on the equivalence between Jordan frame and Einstein frame formulations, which allows us to uniquely construct the energy momentum tensor for non-minimally coupled theories.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Multidisciplinary Sciences
Sergei V. Chervon, Igor V. Fomin
Summary: This study examines scalar-torsion gravity theories with exact solutions based on a physical type of potential for cosmological inflationary models involving the non-minimal coupling of a scalar field and torsion. Different inflationary dynamics and corresponding scalar field parameters are analyzed. This approach allows for the consideration of various physical potentials and types of scalar-torsion gravity theories in the realization of two stages of accelerated expansion in the universe. The correspondence between the proposed inflationary models and observational constraints on cosmological perturbation parameters is also explored.
Article
Astronomy & Astrophysics
Philippe Brax, Anne-Christine Davis, Benjamin Elder
Summary: We derive upper and lower bounds on screened scalar field theories using hydrogenlike systems. Direct coupling between matter and new light scalar fields is heavily constrained by experimental measurements. However, certain theories have screening mechanisms that dynamically weaken this coupling and evade many of these constraints. By computing perturbations to the energy levels of hydrogenlike systems due to screened scalar fields, we find weaker bounds from hydrogen spectroscopy than previously reported. Moreover, we show that muonium experiments are more sensitive probes of screened scalar fields, exploring parameter space that low-energy physics has yet to cover and has only been tested by high-energy particle physics experiments.
Article
Astronomy & Astrophysics
Cristian Erices, Pantelis Filis, Eleftherios Papantonopoulos
Summary: The study demonstrates the avoidance of the no-hair theorem in scalar-tensor theories with bimetric structure by introducing an electric charge, leading to black hole solutions with rich thermodynamic behavior. The interplay of stability and phase transitions between different black hole configurations resembles a solid-liquid-gas system, with an electric potential acting as pressure and a triple point where three phases coexist equally probable.
Article
Physics, Particles & Fields
P. A. Gonzalez, Eleftherios Papantonopoulos, Joel Saavedra, Yerko Vasquez
Summary: This study considers the propagation of charged massive scalar fields in the background of Reissner-Nordstrom-de Sitter black holes and investigates the effect of the scalar field charge on the spectrum of quasinormal frequencies and the anomalous decay rate. The results show that the anomalous behavior also exists for charged massive scalar fields, and there is a critical value that leads to a reversal of this behavior. Additionally, there is a critical value of the charge parameter and the black hole charge, which increases with the cosmological constant, and beyond this critical value, the anomalous behavior of the decay rate can be avoided for the fundamental mode.
JOURNAL OF HIGH ENERGY PHYSICS
(2022)
Article
Astronomy & Astrophysics
Tahere Kashfi, Mahmood Roshan
Summary: In this paper, a recently proposed relativistic theory for MOND is investigated using phase space analysis. The background cosmological equations of the theory are converted to a set of first-order autonomous equations. It is shown that the theory has a viable sequence of cosmological epochs and provides a richer structure in terms of the background cosmology.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Physics, Particles & Fields
Fil Simovic, Danny Fusco, Robert B. Mann
Summary: The thermodynamic properties of 3+1 dimensional black holes conformally coupled to a real scalar field in asymptotically de Sitter spacetimes were investigated using a Euclidean action approach. By treating the cosmological constant as a thermodynamic pressure in the extended phase space, phase transitions resembling Hawking-Page transitions were observed in the black hole solutions, with the existence of these transitions further depending on a specific cosmic censorship bound.
JOURNAL OF HIGH ENERGY PHYSICS
(2021)
Article
Computer Science, Software Engineering
Y. Lu, K. Jiang, J. A. Levine, M. Berger
Summary: The proposed approach presents a method for compressing volumetric scalar fields using implicit neural representations, achieving highly compact representations by quantizing network weights and outperforming state-of-the-art compression methods. The conceptual simplicity of the approach allows for multiple benefits such as support for time-varying scalar fields and random-access field evaluation.
COMPUTER GRAPHICS FORUM
(2021)
Article
Physics, Particles & Fields
P. M. Lavrov
Summary: In this article, the author utilizes a new approach to deal with the deformation procedure in the case of reducible gauge theories. They find that in the model of massless spin 3 fields and a real scalar field, it is not possible to construct local cubic vertices that are invariant under initial gauge transformations, while local quartic gauge-invariant vertices can be constructed.
EUROPEAN PHYSICAL JOURNAL C
(2022)
Article
Astronomy & Astrophysics
Pawan Joshi, Sukanta Panda
Summary: This paper discusses the Ostrogradsky instability issue in nondegenerate higher-order derivative theories, which can be resolved by removing degeneracy in such theories. By decomposing and checking the degeneracy hidden in the Lagrangian, conditions under which the Ostrogradsky instability does not appear can be found.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Valerio Faraoni, Theo B. Franconnet
Summary: This article investigates a puzzle in the recent thermodynamics of scalar-tensor gravity, where general relativity is a zero-temperature equilibrium state and scalar-tensor gravity is the nonequilibrium configuration of an effective dissipative fluid. A stealth solution of Brans-Dicke gravity with constant positive temperature is shown to be analogous to a metastable state for the effective fluid and to suffer from an instability. The stability analysis utilizes a modified gravity version of the Bardeen-Ellis-Bruni-Hwang gauge-invariant formalism for cosmological perturbations. The metastable state is destroyed by tensor perturbations.
Article
Physics, Multidisciplinary
E. E. Kangal, M. Salti, O. Aydogdu, K. Sogut
Summary: In this article, we investigate the Klein-Gordon equation in a topologically trivial Godel-type space-time in the context of rainbow gravity. We obtain exact solutions and energy spectrum of scalar particles for the considered model. Results show that the energy spectrum of scalar particles is modified by rainbow functions compared to the solutions obtained via ordinary general relativity theory.
