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The notion of vacuum fluctuations of the gravitational field plays important role in cosmology. The strong variable gravitational field of the very early Universe amplifies these fluctuations and transforms them into macroscopical…

General Relativity and Quantum Cosmology · Physics 2007-05-23 L. P. Grishchuk

We investigate scaling and correlations of the energy and momentum in an evolving network of cosmic strings in Minkowski space. These quantities are of great interest, as they must be understood before accurate predictions for the power…

Astrophysics · Physics 2009-10-28 Graham R. Vincent , Mark Hindmarsh , Mairi Sakellariadou

We consider a model for gravity that is invariant under global scale transformations. It includes one extra real scalar field coupled non-minimally to the gravity fields. In this model all the dimensionful parameters like the gravitational…

General Relativity and Quantum Cosmology · Physics 2012-02-06 Pankaj Jain , Purnendu Karmakar , Subhadip Mitra , Sukanta Panda , Naveen K. Singh

We consider theories of gravity that include many coupled scalar fields with arbitrary couplings, in the geometric framework of wave maps. We examine the possibility of obtaining acceptable cosmological solutions without the inclusion of a…

General Relativity and Quantum Cosmology · Physics 2019-06-17 Spiros Cotsakis , John Miritzis , Koralia Tzanni

We investigate cosmological correlators for conformally coupled $\phi^4$ theory in four-dimensional de Sitter space. These \textit{in-in} correlators differ from scattering amplitudes for massless particles in flat space due to the…

High Energy Physics - Theory · Physics 2024-03-01 Chandramouli Chowdhury , Arthur Lipstein , Jiajie Mei , Ivo Sachs , Pierre Vanhove

The origin of the large scale structure in the universe - galaxies, quasars, clusters, voids, sheets - is one of the most important questions in cosmology. One can show that some non-thermal energy density fluctuations must have been…

Astrophysics · Physics 2007-05-23 Mairi Sakellariadou

The study addresses matter-coupled modified gravity, particularly $f (T, \mathcal{T})$ gravity, unveiling distinct formalism. The research further discusses stability analysis, and the dynamical system approach, exploring the dynamics of…

General Relativity and Quantum Cosmology · Physics 2023-12-22 L. K. Duchaniya , Santosh V Lohakare , B. Mishra

Quantum cosmology implies corrections to the classical equations of motion which may lead to significant departures from the classical trajectory, especially at high curvature near the big-bang singularity. Corrections could in principle be…

General Relativity and Quantum Cosmology · Physics 2014-09-09 Martin Bojowald , David Simpson

We construct the higher order terms of curvatures in Lagrangians of the scale factor for the Friedmann-Lemaitre-Robertson-Walker universe, which are linear in the second derivative of the scale factor with respect to cosmic time. It is…

General Relativity and Quantum Cosmology · Physics 2013-04-02 Nahomi Kan , Koichiro Kobayashi , Kiyoshi Shiraishi

We investigate cosmological solutions of the chameleon model with a non-minimal coupling between the matter and the scalar field through a conformal factor with gravitational strength. By considering the spatially flat FLRW metric and the…

General Relativity and Quantum Cosmology · Physics 2023-11-01 Raziyeh Zaregonbadi , Nasim Saba , Mehrdad Farhoudi

Universe structure emerges in the unreduced, complex-dynamic interaction process with the simplest initial configuration (two attracting homogeneous fields, quant-ph/9902015). The unreduced interaction analysis gives intrinsically creative…

General Physics · Physics 2007-05-23 Andrei P. Kirilyuk

In this work we consider gravitational theories in which the effect of coupling characteristic classes, appropriately introduced as operators in the Einstein-Hilbert action, has been taken into account. As it is well known, this approach…

General Relativity and Quantum Cosmology · Physics 2016-07-29 J. Lorca Espiro , Yerko Vásquez

Using dynamical systems methods, we describe the evolution of a minimally coupled scalar field and a Friedmann-Lemaitre-Robertson-Walker universe in the context of general relativity, which is relevant for inflation and late-time…

General Relativity and Quantum Cosmology · Physics 2015-06-11 Valerio Faraoni , Charles S. Protheroe

A simple set of diagrammatic rules is formulated for perturbative evaluation of ``in-in" correlators, as is needed in cosmology and other nonequilibrium problems. These rules are both intuitive, and efficient for calculational purposes.

High Energy Physics - Theory · Physics 2014-11-21 Steven B. Giddings , Martin S. Sloth

This work deals with $F(T)$ gravity models driven by real scalar fields with usual and phantom dynamics. We illustrate the results with examples of current interest, and we find some analytical solutions for scale factors and scalar fields.…

General Relativity and Quantum Cosmology · Physics 2010-06-22 K. K. Yerzhanov , Sh. R. Myrzakul , I. I. Kulnazarov , R. Myrzakulov

This work examines a relativistic model for the observed inhomogeneities of the large scale structure where the hypothesis that this structure can be described as being a self-similar fractal system is advanced. The concept of hierarchical…

Astrophysics · Physics 2011-02-11 Marcelo B. Ribeiro

The existence of self-similar solutions is discussed in symmetric teleparallel $f(Q)$-theory for a Friedmann-Lema\^itre-Robertson-Walker background geometry with zero and non-zero spatial curvature. For the four distinct families of…

General Relativity and Quantum Cosmology · Physics 2022-12-01 N. Dimakis , M. Roumeliotis , A. Paliathanasis , P. S. Apostolopoulos , T. Christodoulakis

We investigate hidden symmetries in minimally coupled scalar field cosmology within the FLRW universe, and a perfect fluid with and without interaction to the scalar field. We show that for an exponential potential there exists a set of…

General Relativity and Quantum Cosmology · Physics 2025-12-25 Andronikos Paliathanasis

We study the cosmology on the Friedmann-Lemaitre-Robertson-Walker background in scalar-vector-tensor theories with a broken $U(1)$ gauge symmetry. For parity-invariant interactions arising in scalar-vector-tensor theories with second-order…

General Relativity and Quantum Cosmology · Physics 2018-07-27 Lavinia Heisenberg , Ryotaro Kase , Shinji Tsujikawa

We investigate cosmological models in a recently proposed geometrical theory of gravity, in which the scalar field appears as part of the space-time geometry. We extend the previous theory to include a scalar potential in the action. We…

General Relativity and Quantum Cosmology · Physics 2016-09-14 M. L. Pucheu , F. A. P. Alves-Junior , A. B. Barreto , C. Romero
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