Article
Astronomy & Astrophysics
Dina Traykova, Emilio Bellini, Pedro G. Ferreira, Carlos Garcia-Garcia, Johannes Noller, Miguel Zumalacarregui
Summary: Efforts to constrain theories of late time accelerated expansion have shown that a more careful analysis of their dynamical evolution can lead to narrower prior settings, improving precision constraints. By studying shift-symmetric scalar-tensor theories, a simplified and accurate parameterization method has been proposed, suitable for observing cosmic evolution.
Article
Astronomy & Astrophysics
Genly Leon, Esteban Gonzalez, Alfredo D. Millano, Felipe Orlando Franz Silva
Summary: This paper investigates scalar field cosmologies with a generalized harmonic potential in flat and negatively curved metrics. The interaction between the scalar field and matter is taken into account. Asymptotic methods and averaging theory are used to obtain information about the solution space, and numerical simulations are used to provide evidence for the results.
CLASSICAL AND QUANTUM GRAVITY
(2022)
Article
Physics, Particles & Fields
Hugh Osborn, Andreas Stergiou
Summary: The tensorial equations for non trivial fully interacting fixed points are analyzed for N-component fields with symmetric tensor couplings. Large numbers of irrational fixed points are found numerically, but no solutions saturating the bound are discovered. These examples generally lack unique quadratic invariants in the fields.
JOURNAL OF HIGH ENERGY PHYSICS
(2021)
Article
Physics, Particles & Fields
William H. Pannell, Andreas Stergiou
Summary: In this study, the one-loop beta functions for systems of N-s scalars and N-f fermions interacting via a general potential are analyzed as tensorial equations in 4-epsilon dimensions. Two distinct bounds on combinations of invariants constructed from the couplings are derived and used to prove restrictions on the anomalous dimensions of the elementary fields. The concept of 'levels' of fixed points in scalar-fermion theories is introduced, and the stability properties of fixed points are examined.
JOURNAL OF HIGH ENERGY PHYSICS
(2023)
Article
Astronomy & Astrophysics
Mohsen Khodadi, Reza Pourkhodabakhshi
Summary: The study examines the impact of a novel rotating black hole on the timescale of scalar cloud formation, showing that including a regularization length scale l can shorten the formation time. This reduction in instability growth time improves the prospects for phenomenological detection of new physics.
Article
Astronomy & Astrophysics
Inyong Cho, Jinn-Ouk Gong, Seung Hun Oh
Summary: By investigating the scalar field and cosmological perturbations, we find that the second-order effective energy-momentum tensor (2EMT) is gauge dependent. In the slow-roll stage of inflation, 2EMT exhibits an effective fluid of w 1/4 -1=3 in various gauge conditions.
Article
Astronomy & Astrophysics
Genly Leon, Felipe Orlando Franz Silva
Summary: In this study, local and global phase-space descriptions and averaging methods were used to investigate the qualitative features of solutions for FLRW and Bianchi I metrics in the context of scalar field cosmologies with arbitrary potentials and couplings to matter. Equilibrium points representing various cosmological solutions such as scaling solutions, kinetic-dominated solutions, and vacuum de Sitter solutions associated with the minimum of the potential were obtained, revealing a rich cosmological phenomenology.
CLASSICAL AND QUANTUM GRAVITY
(2021)
Article
Physics, Multidisciplinary
Charlie Cresswell-Hogg, Daniel F. Litim
Summary: In the limit of many fermion flavors, the sextic Gross-Neveu theory in three dimensions exhibits a line of interacting UV fixed points with an exactly marginal sextic interaction. The conformal window of UV-complete theories, universal scaling dimensions, and phase diagram are determined using renormalization group methods. Massless theories occur naturally and mass generation occurs without discrete symmetry breaking. Striking similarities with critical scalar theories at large N are emphasized, along with implications from the perspective of conformal field theory and the AdS=CFT conjecture.
PHYSICAL REVIEW LETTERS
(2023)
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
Astronomy & Astrophysics
Julio C. Fabris, Tales Augusto Oliveira Gomes, Denis Campos Rodrigues
Summary: This paper investigates charged black hole and wormhole solutions in the Einstein-Maxwell system with a massless, real scalar field. By using a conformal transformation, the possible static, spherically symmetric structures in the minimal coupled system are described. Besides wormholes and naked singularities, there exists a restricted class of black holes with an infinite surface and a timelike central singularity.
Article
Astronomy & Astrophysics
Andronikos Paliathanasis
Summary: We discuss a multi-scalar field model in the Jordan frame, which can be seen as a two-scalar field model. We show that the model can provide scaling solutions and de Sitter universe. In the study of asymptotic dynamics, we also identify a spiral attractor.
Article
Astronomy & Astrophysics
Andronikos Paliathanasis
Summary: In this paper, the cosmological dynamics in scalar-tensor and scalar-torsion theories with a nonminimally coupled complex scalar field in a spatially flat Friedmann-Lemaitre-Robertson-Walker geometry are investigated. The cosmological field equations are derived and dimensionless variables are used to determine the stationary points and their stability properties. The physical properties of the stationary points are discussed, revealing common features between the two different theories.
MODERN PHYSICS LETTERS A
(2022)
Article
Physics, Particles & Fields
Gudrun Hiller, Daniel F. Litim, Kevin Moch
Summary: This article investigates weakly interacting fixed points in extensions of the MSSM and finds that most of them are infrared conformal fixed points. It also predicts low-scale supersymmetry-breaking and a violation of R-parity. The article indicates prospects for higher matching scales and asymptotic safety beyond the MSSM.
EUROPEAN PHYSICAL JOURNAL C
(2022)
Article
Multidisciplinary Sciences
Gregory W. Horndeski
Summary: This paper explores how the concept of Finsler geometry can be applied to construct a geometric structure using a scalar field. It investigates the generation of self-inflating universes and multiverses using this structure.
PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES
(2022)
Article
Astronomy & Astrophysics
L. Filipe O. Costa, Lode Wylleman, Jose Natario
Summary: This work clarifies the algebraic and physical meanings of curvature invariants and their electromagnetic counterparts. It explores the conditions for the existence of observers measuring specific fields and tidal tensors, and analyzes the structure of invariants in astrophysical setups. A new classification for intrinsic/extrinsic gravitomagnetism is proposed in the end.
Article
Astronomy & Astrophysics
Laur Jaerv, Manuel Hohmann, Martin Krssak, Christian Pfeifer
Editorial Material
Physics, Mathematical
Christian Pfeifer, Martin Krssak, Tomi Koivisto, Sebastian Bahamonde, Manuel Hohmann, Laur Jarv, Margus Saal
Summary: The paper studies spherical symmetry in a modified teleparallel theory of gravity based on an arbitrary function of five possible scalars constructed from the irreducible parts of torsion. The theory is a generalization of the New General Relativity theory. The study analytically solves the corresponding field equations for conformal Teleparallel gravity and perturbatively around Schwarzschild geometry for the general perturbative theory around GR, ultimately computing phenomenological effects from the perturbed solutions.
INTERNATIONAL JOURNAL OF GEOMETRIC METHODS IN MODERN PHYSICS
(2021)
Article
Astronomy & Astrophysics
Laur Jarv, Joosep Lember
Summary: Global phase portraits of inflationary dynamics in teleparallel gravity models with scalar fields nonminimally coupled to torsion scalar are constructed, focusing on distinguishing different asymptotic states and identifying the key role of heteroclinic orbits and asymptotic fixed points. Effective potential and effective mass provide a heuristic method for seeking asymptotic fixed points, applicable to any nonminimally coupled theories. Specific examples of positive quadratic nonminimal couplings with quadratic and quartic potentials are studied, showing qualitative differences from scalar-curvature counterparts.
Article
Physics, Particles & Fields
Laur Jarv, Alexey Toporensky
Summary: This study reconsiders the dynamical systems approach to analyze inflationary universe in the Jordan frame models of scalar field nonminimally coupled to curvature. It finds that the adopted set of variables allows clear distinction between different asymptotic states including the kinetic and inflationary regimes. The study also provides a comprehensive picture of possible initial conditions leading to sufficient inflationary expansion and shows how they approximate the leading inflationary attractor solution. Additionally, it examines the impact of nonminimal coupling on the range of good initial conditions using quadratic and quartic potential models as examples.
EUROPEAN PHYSICAL JOURNAL C
(2022)
Article
Astronomy & Astrophysics
Sebastian Bahamonde, Jorge Gigante Valcarcel, Laur Jarv
Summary: In this study, we construct Plebanski-Demianski stationary and axisymmetric solutions with two expanding and double principal null directions in the framework of Metric-Affine gauge theory of gravity. We explore the black hole configurations characterized by various physical parameters and reveal the conditions under which the torsion and nonmetricity tensors provide dynamical contributions and their effects on the geometry of space-time.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Sebastian Bahamonde, Jorge Gigante Valcarcel, Laur Jarv, Joosep Lember
Summary: This paper investigates the scalar-tensor theories built with a nonminimal coupling between the nonmetricity scalar and a scalar field in the framework of symmetric teleparallel gravity. Exact scalarised spherically symmetric static solutions are found, and it is discovered that some of these solutions describe scalarised black hole configurations that are not known in the Riemannian or metric teleparallel scalar-tensor case.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Physics, Particles & Fields
Sebastian Bahamonde, Laur Jarv
Summary: This paper investigates the coincident gauge in static spherically symmetric spacetime configurations and provides the corresponding metrics. It is found that different connections result in different values for the boundary term, and simple arguments about the coincident gauge are not sufficient to uniquely determine the connection.
EUROPEAN PHYSICAL JOURNAL C
(2022)
Article
Astronomy & Astrophysics
Sebastian Bahamonde, Jorge Gigante Valcarcel, Laur Jarv, Christian Pfeifer
Summary: This paper examines axial spacetimes in teleparallel gravity and the determination of spin connection, analyzing solutions through the study of symmetric and antisymmetric equations, and demonstrating the feasibility of solutions through specific examples.
Article
Astronomy & Astrophysics
Laur Jarv, Alexandros Karam, Aleksander Kozak, Angelos Lykkas, Antonio Racioppi, Margus Saal
Article
Astronomy & Astrophysics
Manuel Hohmann, Laur Jarv, Martin Krssak, Christian Pfeifer
Article
Astronomy & Astrophysics
Manuel Hohmann, Laur Jarv, Martin Krssak, Christian Pfeifer
Article
Astronomy & Astrophysics
Laur Jarv, Mihkel Runkla, Margus Saal, Ott Vilson
Article
Astronomy & Astrophysics
Laur Jarv, Antonio Racioppi, Tommi Tenkanen
Article
Astronomy & Astrophysics
Manuel Hohmann, Laur Jaerv, Ulbossyn Ualikhanova
Article
Astronomy & Astrophysics
Hmar Zonunmawia, Wompherdeiki Khyllep, Jibitesh Dutta, Laur Jarv
