Results 31 to 40 of about 973 (226)
COSMOLOGICAL PERTURBATIONS IN PRESENCE OF SCALAR FIELDS
Odessa Astronomical Publications, 2014 We investigate the role of the scalar field assuming its presence at late stages of the Universe evolution together with dust presented by a system of an arbitrary number of gravitating masses (galaxies, groups of galaxies and clusters of galaxies) and ...
A. Yu. Burgazli, M. Eingorn, A. Zhuk
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Black hole perturbation theory and multiple polylogarithms
Journal of High Energy Physics, 2023 We study black hole linear perturbation theory in a four-dimensional Schwarzschild (anti) de Sitter background. When dealing with a positive cosmological constant, the corresponding spectral problem is solved systematically via the Nekrasov-Shatashvili ...
Gleb Aminov +4 more
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PERTURBATIONS IN BOUNCING COSMOLOGICAL MODELS [PDF]
International Journal of Modern Physics D, 2004 I describe the features and general properties of bouncing models and the evolution of cosmological perturbations on such backgrounds. I will outline possible observational consequences of the existence of a bounce in the primordial Universe and I will make a comparison of these models with standard long inflationary scenarios.
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Cosmological perturbations engendered by discrete relativistic species
European Physical Journal C: Particles and Fields, 2023 Within the extension of the $$\varLambda $$ Λ CDM model, allowing for the presence of neutrinos or warm dark matter, we develop the analytical cosmological perturbation theory.
Maksym Brilenkov +2 more
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Semiclassicality and decoherence of cosmological perturbations [PDF]
Classical and Quantum Gravity, 1996 Revised version to appear in Class. Quantum Grav. All prior conclusions hold.
Polarski, David, Starobinsky, Alexei A.
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Quantum Gravity and Cosmological Density Perturbations
Galaxies, 2014 We explore the possible cosmological consequences of a running Newton’s constant, G(⎕), as suggested by the non-trivial ultraviolet fixed point scenario for Einstein gravity with a cosmological constant term.
Herbert W. Hamber, Reiko Toriumi
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Cosmological perturbations on the phantom brane [PDF]
Journal of Cosmology and Astroparticle Physics, 2016 We obtain a closed system of equations for scalar perturbations in a multi-component braneworld. Our braneworld possesses a phantom-like equation of state at late times, $w_{\rm eff} < -1$, but no big-rip future singularity. In addition to matter and radiation, the braneworld possesses a new effective degree of freedom - the 'Weyl fluid' or 'dark ...
Bag, Satadru +3 more
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Theory of cosmological perturbations with cuscuton [PDF]
Journal of Cosmology and Astroparticle Physics, 2017 This paper presents the first derivation of the quadratic action for curvature perturbations, $ζ$, within the framework of cuscuton gravity. We study the scalar cosmological perturbations sourced by a canonical single scalar field in the presence of cuscuton field.
Boruah, Supranta S. +2 more
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Cosmological perturbations in unimodular gravity [PDF]
Journal of Cosmology and Astroparticle Physics, 2014 We study cosmological perturbation theory within the framework of unimodular gravity. We show that the Lagrangian constraint on the determinant of the metric required by unimodular gravity leads to an extra constraint on the gauge freedom of the metric perturbations. Although the main equation of motion for the gravitational potential remains the same,
Gao, Caixia +3 more
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Non-minimal coupling influence on the deviation from de Sitter cosmological expansion
European Physical Journal C: Particles and Fields, 2018 We investigate the models of cosmological inflation in generalized scalar–tensor gravity, which we consider as a source of deviation from de Sitter dynamics in the case of GR.
I. V. Fomin, S. V. Chervon
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