Results 11 to 20 of about 507 (119)

$$f(\mathcal {G})$$ f(G) Noether cosmology

European Physical Journal C: Particles and Fields, 2020
We develop the n-dimensional cosmology for $$f(\mathcal {G})$$ f(G) gravity, where $$\mathcal {G}$$ G is the Gauss–Bonnet topological invariant. Specifically, by the so-called Noether Symmetry Approach, we select $$f(\mathcal {G})\simeq \mathcal {G}^k ...
Francesco Bajardi, Salvatore Capozziello
doaj   +1 more source

Minisuperspace Quantum Cosmology in Metric and Affine Theories of Gravity

Universe, 2022
Minisuperspace Quantum Cosmology is an approach by which it is possible to infer initial conditions for dynamical systems which can suitably represent observable and non-observable universes. Here we discuss theories of gravity which, from various points
Salvatore Capozziello, Francesco Bajardi
doaj   +1 more source

Conformal structure of FLRW cosmology: spinorial representation and the so $$ \mathfrak{so} $$ (2, 3) algebra of observables

Journal of High Energy Physics, 2020
It was recently shown that the homogeneous and isotropic cosmology of a massless scalar field coupled to general relativity exhibits a new hidden conformal invariance under Mobius transformation of the proper time, additionally to the invariance under ...
Jibril Ben Achour, Etera R. Livine
doaj   +1 more source

Two-photon amplitude interferometry for precision astrometry

The Open Journal of Astrophysics, 2022
Improved quantum sensing of photons from astronomical objects could provide high resolution observations in the optical benefiting numerous fields, including general relativity, dark matter studies, and cosmology.
Paul Stankus, Andrei Nomerotski, Anže Slosar, Stephen Vintskevich   +3 more
doaj   +1 more source

Dark Energy Problem, Physics of Early Universe and Some New Approaches in Gravity

Entropy, 2012
The dark energy problem is studied based on the approach associated with the cosmological term in General Relativity that is considered as a dynamic quantity.
Alexander Shalyt-Margolin
doaj   +1 more source

The Vacuum State of Primordial Fluctuations in Hybrid Loop Quantum Cosmology

Universe, 2018
We investigate the role played by the vacuum of the primordial fluctuations in hybrid Loop Quantum Cosmology. We consider scenarios where the inflaton potential is a mass term and the unperturbed quantum geometry is governed by the effective dynamics of ...
Beatriz Elizaga Navascués, Daniel Martín de Blas, Guillermo A. Mena Marugán   +2 more
doaj   +1 more source

Effective f(R) Actions for Modified Loop Quantum Cosmologies via Order Reduction

Universe, 2023
General Relativity is an extremely successful theory, at least for weak gravitational fields; however, it breaks down at very high energies, such as in correspondence to the initial singularity.
Ana Rita Ribeiro, Daniele Vernieri, Francisco S. N. Lobo   +2 more
doaj   +1 more source

Complex Riemannian Spacetime and Singularity-Free Black Holes and Cosmology

Axioms
An approach is presented to address singularities in general relativity using a complex Riemannian spacetime extension. We demonstrate how this method can be applied to both black hole and cosmological singularities, specifically focusing on the ...
John W. Moffat
doaj   +1 more source

Tests of standard cosmology in Hořava gravity, Bayesian evidence for a closed universe, and the Hubble tension

European Physical Journal C: Particles and Fields, 2022
We consider some background tests of standard cosmology in the context of Hořava gravity with different scaling dimensions for space and time, which has been proposed as a renormalizable, higher-derivative, Lorentz-violating quantum gravity model without
Nils A. Nilsson, Mu-In Park
doaj   +1 more source

Group Field Theory and Its Cosmology in a Matter Reference Frame

Universe, 2018
While the equations of general relativity take the same form in any coordinate system, choosing a suitable set of coordinates is essential in any practical application.
Steffen Gielen
doaj   +1 more source