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In this work, we revisit the dynamics of pre-inflationary universe with a family of $\alpha-$attractor potentials, in the framework of loop quantum cosmology, in which the big bang singularity is generically resolved purely with quantum…

General Relativity and Quantum Cosmology · Physics 2020-09-22 M. Shahalam , Mudhahir Al Ajmi , R. Myrzakulov , Anzhong Wang

We study a particular exact solution to the Born-Infeld determinantal gravity consisting of a cosmological model which undergoes a brusque bounce. The latter consists of an event characterized by a non-null (but finite) value of the squared…

General Relativity and Quantum Cosmology · Physics 2016-07-20 Franco Fiorini

We explore bounce scenarios in the framework of homogeneous and isotropic cosmological models with arbitrary spatial curvature in the theory of gravity with non-minimal derivative coupling. As expected, we find that there are no turning…

General Relativity and Quantum Cosmology · Physics 2025-02-11 S. V. Sushkov , R. G. Galeev

We investigate the existence of black bounce solutions in $2+1$ dimensions within the framework of $f(R)$ gravity. We analyze whether black bounce geometries originally obtained in general relativity can be consistently generalized to…

General Relativity and Quantum Cosmology · Physics 2026-04-09 Marcos V. de S. Silva , Manuel E. Rodrigues , C. F. S. Pereira

We present a stable cosmological model of a closed universe in the presence of conventional scalar field. The stability of the model and absence of singularity is ensured by spatial curvature without the need for additional peculiar matter.…

General Relativity and Quantum Cosmology · Physics 2025-04-29 Rinat Kagirov

The inflationary paradigm, although very successful phenomenologically, suffers from several conceptual problems which motivate the search for alternative scenarios of early universe cosmology. Here, two possible alternatives will be…

High Energy Physics - Theory · Physics 2015-05-13 Robert H. Brandenberger

We offer a new proposal for cosmic singularity resolution based upon a quantum cosmology with a unitary bounce. This proposal is illustrated via a novel quantization of a mini-superspace model in which there can be superpositions of the…

General Relativity and Quantum Cosmology · Physics 2018-12-17 Sean Gryb , Karim P. Y. Thébault

We explore bounce cosmology in $F(\mathcal{G})$ gravity with the Gauss-Bonnet invariant $\mathcal{G}$. We reconstruct $F(\mathcal{G})$ gravity theory to realize the bouncing behavior in the early universe and examine the stability…

High Energy Physics - Theory · Physics 2014-04-17 Kazuharu Bamba , Andrey N. Makarenko , Alexandr N. Myagky , Sergei D. Odintsov

The Pre-Big Bang cosmology inspired generations of cosmologists in attempts to cure the initial Big Bang singularity using a fundamental length scale as proposed by String Theory. The existence of a phase of collapse/inflation with…

General Relativity and Quantum Cosmology · Physics 2022-07-14 V. Bozza

We find a solution for exponential inflation in Brans-Dicke cosmology endowed with a cosmological term, which includes time-varying shear and vorticity. We find that the scalar field and the scale factor increase exponentialy while shear,…

General Physics · Physics 2008-11-26 Marcelo Samuel Berman

In a systematic study, we use an equivalent pair of improved numerical relativity codes based on a tetrad-formulation of the classical Einstein-scalar field equations to examine whether slow contraction or inflation (or both) can resolve…

General Relativity and Quantum Cosmology · Physics 2024-04-03 Anna Ijjas , Paul J. Steinhardt , David Garfinkle , William G. Cook

Investigations of the dynamic modes of the Poincare gauge theory of gravity found only two good propagating torsion modes; they are effectively a scalar and a pseudoscalar. Cosmology affords a natural situation where one might see…

General Relativity and Quantum Cosmology · Physics 2008-12-18 Kun-Feng Shie , James M. Nester , Hwei-Jang Yo

The full set of cosmological observables coming from linear scalar and tensor perturbations of loop quantum cosmology is computed in the presence of inverse-volume corrections. Background inflationary solutions are found at linear order in…

General Relativity and Quantum Cosmology · Physics 2011-03-28 Martin Bojowald , Gianluca Calcagni

A new class of a spatially homogeneous and anisotropic Bianchi type-I cosmological models of the universe for perfect fluid distribution within the framework of scalar-tensor theory of gravitation proposed by Saez and Ballester (Phys. Lett.…

General Physics · Physics 2012-11-15 Anirudh Pradhan , Ajay Kumar Singh , H. Amirhashchi

Velocity and density structure factors are measured over a hydrodynamic range of scales in a horizontal quasi-2d fluidized granular experiment, with packing fractions $\phi\in[10%,40%]$. The fluidization is realized by vertically vibrating…

Soft Condensed Matter · Physics 2015-06-03 A. Puglisi , A. Gnoli , G. Gradenigo , A. Sarracino , D. Villamaina

We investigate classically non-singular bounces caused by dark energy. In the presence of positive spatial curvature, vacuum energy, either in the form of a cosmological constant or a scalar field potential, allows for an open set of…

High Energy Physics - Theory · Physics 2019-06-26 Sebastian F. Bramberger , Jean-Luc Lehners

The spin-torsion fluctuations are shown to act as source of decay of inhomogeneities in the early stages of inflationary de Sitter universe.This seems to be a resul of the repulsive nature of the spin-torsion effects.This result is shown…

Astrophysics · Physics 2007-05-23 L. C. Garcia de Andrade

Certain features in the primordial scalar power spectrum are known to improve the fit to the cosmological data. We examine whether bouncing scenarios can remain viable if future data confirm the presence of such features. In inflation, the…

Cosmology and Nongalactic Astrophysics · Physics 2019-02-27 Rathul Nath Raveendran , L. Sriramkumar

We analyse an inhomogeneous cosmological model featuring a spherically symmetric bubble solution induced by a unified single perfect fluid, comprising spatially dependent Dark Energy (with $w=-1$) and Dark Matter (with $w=0$) components. We…

General Relativity and Quantum Cosmology · Physics 2025-01-15 D. Comelli

Inflationary models are generally credited with explaining the large scale homogeneity, isotropy, and flatness of our universe as well as accounting for the origin of structure (i.e., the deviations from exact homogeneity) in our universe.…

General Relativity and Quantum Cosmology · Physics 2015-06-25 Stefan Hollands , Robert M. Wald