Article
Physics, Nuclear
Mingzhe Li, Yicen Mou, Haomin Rao, Dehao Zhao
Summary: This study investigates the possibilities of generating baryon number asymmetry under thermal equilibrium within the frameworks of teleparallel and symmetric teleparallel gravities, finding that gravitational baryogenesis mechanisms in these frameworks produce a baryon-to-entropy ratio too small to be consistent with observations, but gravitational leptogenesis models within both frameworks have the potential to explain the observed baryon-antibaryon asymmetry.
Article
Astronomy & Astrophysics
Mingzhe Li, Dehao Zhao
Summary: This paper explores the cosmological applications and features of cosmological perturbations in parity violating models based on symmetric teleparallel gravity. It reveals that in addition to the known parity violation in tensor perturbations, vector perturbations in this model exhibit unique characteristics, with one mode behaving as a ghost at high momentum scales, leading to vacuum instability in the quantum theory of cosmological perturbations.
Article
Astronomy & Astrophysics
Andronikos Paliathanasis
Summary: This article investigates the application of symmetric teleparallel f(Q)-gravity in Friedmann-Lemaître-Robertson-Walker cosmology with nonzero spatial curvature. It is found that for a nonlinear f(Q) model, there always exists the limit of General Relativity. The de Sitter solution is identified as the unique attractor, and deviations from STGR can solve the flatness problem.
PHYSICS OF THE DARK UNIVERSE
(2023)
Article
Physics, Multidisciplinary
Sanjay Mandal, N. Myrzakulov, P. K. Sahoo, R. Myrzakulov
Summary: Symmetric teleparallel gravity is a theory consistent with the vanishing affine connection and serves as an alternative and simpler geometric formulation of general relativity. Researchers have explored cosmological bouncing scenarios in a flat Friedmann-Limaitre-Robertson-Walker spacetime using two different Lagrangian forms of f(Q). Analysis of energy conditions and stability has been successfully conducted for both models to demonstrate a matter bounce.
EUROPEAN PHYSICAL JOURNAL PLUS
(2021)
Article
Physics, Multidisciplinary
N. Myrzakulov, M. Koussour, A. Mussatayeva
Summary: In this study, the cosmological history within the framework of modified f(Q) gravity is investigated. The exact solution to the field equations in f(Q) cosmology is obtained using a parametrization scheme for the Hubble parameter. External datasets are utilized to constrain the model and analyze the cosmic evolution of various cosmological parameters. The findings demonstrate that the late-time cosmic evolution can be adequately described without the need for dark energy by employing a parametrization scheme in modified gravity.
CHINESE JOURNAL OF PHYSICS
(2023)
Review
Physics, Multidisciplinary
Sebastian Bahamonde, Konstantinos F. Dialektopoulos, Celia Escamilla-Rivera, Gabriel Farrugia, Viktor Gakis, Martin Hendry, Manuel Hohmann, Jackson Levi Said, Jurgen Mifsud, Eleonora Di Valentino
Summary: In this Review, the development of teleparallel gravity as a gauge theory of translations is comprehensively introduced. The construction of consistent teleparallel theories that respect physical conditions such as local Lorentz invariance is described. Various modified teleparallel theories of gravity are discussed and connected into general classes of covariant gravitational theories. The cosmological consequences and observational implications of teleparallel gravity are also explored, along with the application of machine learning to gravity research.
REPORTS ON PROGRESS IN PHYSICS
(2023)
Article
Astronomy & Astrophysics
Prabir Rudra
Summary: In this work, the f(Q, T-mu nu T-mu nu) gravity theory is proposed as an extension of the f(Q) and f(Q, T) gravity theories. The theory involves an arbitrary function of the non-metricity Q and T-2 = T-mu nu T-mu nu, and the field equations are derived in the metric-affine formalism. The theory exhibits a non-minimal coupling between the geometric and the matter sectors, leading to a non-zero covariant divergence of the energy-momentum tensor. The theory is capable of explaining the cosmological dynamics of both the early and the late universe without the need for dark energy.
PHYSICS OF THE DARK UNIVERSE
(2022)
Article
Physics, Particles & Fields
Lavinia Heisenberg, Manuel Hohmann, Simon Kuhn
Summary: We derive the most general homogeneous and isotropic teleparallel geometries, defined by a metric and a flat, affine connection. We find that there are five branches of connection solutions, which are connected via several limits, and can further be restricted to the torsion-free and metric-compatible cases. We apply our results to several classes of general teleparallel gravity theories and derive their cosmological dynamics for all five branches. Our results show that for large subclasses of these theories the dynamics reduce to that of closely related metric or symmetric teleparallel gravity theories, while for other subclasses up to two new scalar degrees of freedom participate in the cosmological dynamics.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Astronomy & Astrophysics
Jose Beltran Jimenez, Tomi S. Koivisto
Summary: In this paper, a general framework for constructing the Einstein frame within non-linear extensions of teleparallel equivalents of General Relativity is provided. It is shown that all non-linear extensions share the same quadratic action around Minkowski backgrounds. Additionally, the conformal mode can be absorbed into a Weyl rescaling of the metric at this order, disappearing from the linear spectrum.
Article
Physics, Multidisciplinary
M. Koussour, S. Dahmani, M. Bennai, T. Ouali
Summary: In this paper, the authors examined a modified symmetric teleparallel gravity theory where the gravitational Lagrangian is defined by an arbitrary function of a non-metricity scalar Q. They used data from OHD and Pantheon+ datasets to constrain the model parameters and found that the obtained results were consistent with observation values. They studied the physical behavior of cosmological parameters and confirmed that the models described the current acceleration of the Universe's expansion. The EoS parameter indicated that the cosmological fluid behaved like a quintessence dark energy model.
EUROPEAN PHYSICAL JOURNAL PLUS
(2023)
Article
Astronomy & Astrophysics
A. A. Coley, R. J. van den Hoogen, D. D. McNutt
Summary: In F(T) teleparallel gravity, determining an appropriate frame and spin connection is a challenge. This paper presents the general form of the coframe and spin connection for teleparallel geometries invariant under affine symmetries, and provides the corresponding F(T) field equations for these geometries.
CLASSICAL AND QUANTUM GRAVITY
(2022)
Article
Astronomy & Astrophysics
Mingzhe Li, Yeheng Tong, Dehao Zhao
Summary: The study examines a parity violating gravity model where ghost instability is a common problem, but under certain conditions, it can be ghost free.
Article
Physics, Particles & Fields
Ji-Yu Cheng
Summary: This paper provides a straightforward proof of the validity of Birkhoff's theorem in modified teleparallel equivalent theories of gravity, which states that if the matter distribution is spherically symmetric, then the spacetime is static in a region where t remains timelike and (r, theta, phi) stay spacelike. This version of Birkhoff's theorem is rather trivial. The theorem also reveals that the gravitational field of a spherically symmetric distribution of matter and of the spherically symmetric vacuum spacetime are both static in modified teleparallel equivalent theories of gravity.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Astronomy & Astrophysics
Reginald Christian Bernardo, Che-Yu Chen, Jackson Levi Said, Yu-Hsien Kung
Summary: This study investigates the effects of quantum fluctuations on the late Universe and explores a representative model with quantum fluctuations embedded in modified gravitational theories. The results suggest mild support for quantum corrections in cosmological models.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
M. Koussour, S. H. Shekh, M. Bennai
Summary: In this paper, a spatially homogeneous and isotropic FLRW cosmological model is studied within the framework of symmetric teleparallel f(Q) gravity. The validity of two specific forms of the f(Q) gravity function is discussed, along with the comparison with observational data.
JOURNAL OF HIGH ENERGY ASTROPHYSICS
(2022)
