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We investigate the gravitational wave background induced by the first order scalar perturbations in the curvaton models. We consider the quadratic and axion-like curvaton potential which can generate the blue-tilted power spectrum of…

Cosmology and Nongalactic Astrophysics · Physics 2013-09-09 Masahiro Kawasaki , Naoya Kitajima , Shuichiro Yokoyama

The primordial Universe can be used as a laboratory to set constraints on quantum gravity. In the framework of Loop Quantum Cosmology, we show that such a proposal for quantum gravity not only solves for the big bang singularity issue but…

General Relativity and Quantum Cosmology · Physics 2012-06-08 Julien Grain

Loop quantum gravity is one of the leading candidate theory to non-perturbatively quantize gravity. In this framework, holonomy corrections to the equation of propagation of gravitons in a FLRW background have been derived. We investigate…

General Relativity and Quantum Cosmology · Physics 2008-05-06 A. Barrau , J. Grain

In this review, we discuss effects of quantum gravity on black hole physics. After a brief review of the origin of the minimal observable length from various quantum gravity theories, we present the tunneling method. To incorporate quantum…

General Relativity and Quantum Cosmology · Physics 2014-10-21 Deyou Chen , Houwen Wu , Haitang Yang , Shuzheng Yang

Gravitational wave (GW) backgrounds of cosmological origin are expected to be nearly isotropic, with small anisotropies resembling those of the cosmic microwave background. We analyse the case of a scalar-induced GW background and clarify…

Cosmology and Nongalactic Astrophysics · Physics 2023-01-18 Ema Dimastrogiovanni , Matteo Fasiello , Ameek Malhotra , Gianmassimo Tasinato

We prove the existence of a spectral resolution of the Wheeler-DeWitt equation when the underlying spacetime is a Friedman universe with flat spatial slices and where the matter fields are comprised of the strong interaction, with $\SU(3)$…

General Relativity and Quantum Cosmology · Physics 2010-07-27 Claus Gerhardt

We study the effects of an information-theoretically motivated nonlinear correction to the Wheeler-deWitt equation in the minisuperspace scheme for flat, $k=0$, Friedmann-Robertson-Walker (FRW) universes. When the only matter is a…

General Relativity and Quantum Cosmology · Physics 2014-11-18 Le-Huy Nguyen , Rajesh R. Parwani

Some results of author's work in a non-geometrical approach to quantum gravity are reviewed here, among them: a quantum mechanism of classical gravity giving a possibility to compute the Newton constant; asymptotic freedom at short…

General Physics · Physics 2009-05-26 Michael A. Ivanov

We consider minisuperspace models constituted of Bianchi I geometries with a free massless scalar field. The classical solutions are always singular (with the trivial exception of flat space-time), and always anisotropic once they begin…

General Relativity and Quantum Cosmology · Physics 2009-10-31 N. Pinto-Neto , A. F. Velasco , R. Colistete

Field self-interactions are at the origin of the non-linearities inherent to General Relativity. We study their effects on the Cosmic Microwave Background anisotropies. We find that they can reduce or alleviate the need for dark matter and…

General Relativity and Quantum Cosmology · Physics 2022-06-02 A. Deur

The quantum gravity processes that have taken place in the very early Universe are probably responsible for the observed large-scale cosmological perturbations. The comparison of the theory with the detected microwave background…

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

We study approximate solutions of the Wheeler DeWitt (WdW) equation and compare them with the standard results of cosmological perturbation theory. In mini-superspace, we introduce a dimensionless gravitational coupling $\alpha$ that is…

High Energy Physics - Theory · Physics 2025-01-23 Federico Piazza , Siméon Vareilles

Quantum cosmology is studied within the framework of the minimal quantum gravity theory proposed by Ho\v{r}ava. For this purpose we choose the Kantowski-Sachs (KS) model and construct the corresponding Wheeler-DeWitt equation. We study the…

General Relativity and Quantum Cosmology · Physics 2013-05-31 O. Obregón , J. A. Preciado

A new method for modelling spherically symmetric inhomogeneities is applied to the formation of clusters in an expanding Universe. We impose simple initial velocity and density perturbations of finite extent and we investigate the…

Astrophysics · Physics 2009-10-31 Y. Dabrowski , M. P. Hobson , A. N. Lasenby , C. J. L. Doran

In this paper we introduce a modified covariant quantum algebra based in the so-called Quesne-Tkachuk algebra. By means of a deformation procedure we arrive at a class of higher derivative models of gravity. The study of the particle…

High Energy Physics - Theory · Physics 2017-10-06 G. P. de Brito , P. I. C. Caneda , Y. M. P. Gomes , J. T. Guaitolini Junior , V. Nikoofard

We show that cosmological quantum relaxation predicts an anisotropic primordial power spectrum with a specific dependence on wavenumber k. We explore some of the consequences for precision measurements of the cosmic microwave background…

Cosmology and Nongalactic Astrophysics · Physics 2015-10-12 Antony Valentini

Several anomalies appear to be present in the large-angle cosmic microwave background (CMB) anisotropy maps of WMAP. One of these is a lack of large-scale power. Because the data otherwise match standard models extremely well, it is natural…

Astrophysics · Physics 2008-12-18 Emory F. Bunn , Austin Bourdon

We explore the consequences of loop quantum cosmology (inverse-volume corrections) in the spectrum of the gravitational waves using the method of the Bogoliubov coefficients. These corrections are taken into account at the background level…

General Relativity and Quantum Cosmology · Physics 2014-01-22 Joao Morais , Mariam Bouhmadi-Lopez , Alfredo B. Henriques

We study the effect of a stochastic background of gravitational waves on the gravitational lensing of the Cosmic Microwave Background (CMB) radiation. It has been shown that matter density inhomogeneities produce a smoothing of the acoustic…

Astrophysics · Physics 2016-08-30 Silvia Mollerach

We study the effects of sudden change in the sound velocity on primordial curvature perturbation spectrum in inflationary cosmology, assuming that the background evolution satisfies the slow-roll condition throughout. It is found that the…

Cosmology and Nongalactic Astrophysics · Physics 2011-06-03 Masahiro Nakashima , Ryo Saito , Yu-ichi Takamizu , Jun'ichi Yokoyama