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How well can we constrain the initial quantum state of metric perturbations sourced during inflation? We exhibit an interesting new class of quantum states that entangle the scalar metric perturbations {\zeta} with other fields such as…

High Energy Physics - Theory · Physics 2018-06-04 Andreas Albrecht , Nadia Bolis , R. Holman

In this article we discuss the role of current and future CMB measurements in pinning down the model of inflation responsible for the generation of primordial curvature perturbations. By considering a parameterization of the effective field…

High Energy Physics - Theory · Physics 2014-10-03 Rhiannon Gwyn , Gonzalo A. Palma , Mairi Sakellariadou , Spyros Sypsas

We present a simple, exact and self-consistent cosmology with a phenomenological model of quantum creation of radiation due to decay of the scalar field. The decay drives a non-isentropic inflationary epoch, which exits smoothly to the…

General Relativity and Quantum Cosmology · Physics 2015-06-25 Alexei Nesteruk

The physical history of the Universe is completed by including the quantum planckian and trans-planckian phase before Inflation in the Standard Model of the Universe in agreement with observations. A new quantum precursor phase appears…

General Relativity and Quantum Cosmology · Physics 2019-12-23 Norma G. Sanchez

We investigate observational constraints on inflationary parameters in the context of an holographic cosmology with an induced gravity correction. We consider two situations where a universe is firstly filled with a scalar field and…

High Energy Physics - Theory · Physics 2020-04-21 Aatifa Bargach , Farida Bargach , Ahmed Errahmani , Taoufik Ouali

This article provides an introductory review of inflation and cosmological perturbation theory. I begin by motivating the need for an epoch of inflation during the early stages of the radiation dominated era, and describe how inflation is…

Cosmology and Nongalactic Astrophysics · Physics 2024-07-08 L. Sriramkumar

Quantum reduced loop gravity is designed to consistently study symmetry reduced systems within the loop quantum gravity framework. In particular, it bridges the gap between the effective cosmological models of loop quantum cosmology and the…

General Relativity and Quantum Cosmology · Physics 2018-12-05 Emanuele Alesci , Aurélien Barrau , Gioele Botta , Killian Martineau , Gabriele Stagno

We construct a class of single small field models of inflation that can predict, contrary to popular wisdom, an observable gravitational wave signal in the cosmic microwave background anisotropies. The spectral index, its running, the…

Cosmology and Nongalactic Astrophysics · Physics 2014-11-20 Ido Ben-Dayan , Ram Brustein

According to the theory of cosmic inflation, the large scale structures observed in our Universe (galaxies, clusters of galaxies, Cosmic Background Microwave - CMB - anisotropy ...) are of quantum mechanical origin. They are nothing but…

Quantum Physics · Physics 2019-04-02 Jerome Martin

Quantum cosmology has traditionally been studied at the level of symmetry-reduced minisuperspace models, analyzing the behavior of wave functions. However, in the absence of a complete full setting of quantum gravity and detailed knowledge…

General Relativity and Quantum Cosmology · Physics 2012-09-18 Martin Bojowald

Within the inflationary scenario, Planck scale physics should have affected the comoving modes' initial conditions and early evolution, thereby potentially affecting the inflationary predictions for the cosmic microwave background (CMB).…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Achim Kempf , Larissa Lorenz

Inflationary scenario based on a renormalizable model of conformal gravity is proposed and primordial spectrum is derived. The sharp fall off of the angular power spectra at low multipoles in the COBE and WMAP observations are explained by…

High Energy Physics - Theory · Physics 2007-05-23 Ken-ji Hamada , Tetsuyuki Yukawa

We reevaluate the predictions of inflation regarding primordial gravity waves, which should appear as B-modes in the CMB, in light of the fact that the standard inflationary paradigm is unable to account for the transition from an initially…

General Relativity and Quantum Cosmology · Physics 2017-11-22 Gabriel León , Abhishek Majhi , Elias Okon , Daniel Sudarsky

We find the best-fit cosmological parameters for a scenario of inflation with only the sufficient amount of accelerated expansion for the $\lambda\phi^4$ potential. While for the simplest scenario of chaotic inflation all observable…

Cosmology and Nongalactic Astrophysics · Physics 2012-06-25 Erandy Ramirez , Dominik J. Schwarz

In this short note we consider the decoherence of the minisuperspace background degrees of freedom due to the long wavelength scalar and tensor perturbations becoming unobservable within the Born-Oppenheimer approach to the quantum gravity.…

General Relativity and Quantum Cosmology · Physics 2021-12-14 Oleg O. Novikov , Arina M. Shtennikova

The evolution of a scalar field is explored taking into account the presence of a background fluid in a positively curved Universe in the framework of loop quantum cosmology. Though the mechanism that provides the initial conditions for…

Astrophysics · Physics 2009-11-13 N. J. Nunes

Inflation may have been driven by a component which violated the Null-Energy Condition, thereby leading to {\it super inflation}. We provide the formalism to study cosmological perturbations when such a component is described by a scalar…

Astrophysics · Physics 2010-09-21 Marco Baldi , Fabio Finelli , Sabino Matarrese

In this review, we focus on whether a canonical quantization of general relativity can produce testable predictions for cosmology. In particular, we examine how this approach can be used to model the evolution of primordial perturbations.…

General Relativity and Quantum Cosmology · Physics 2023-10-20 Leonardo Chataignier , Claus Kiefer , Paulo Moniz

Recent cosmic microwave background (CMB) observations put strong constraints on the spatial curvature via estimation of the parameter $\Omega_k$ assuming an almost scale invariant primordial power spectrum. We study the evolution of the…

Cosmology and Nongalactic Astrophysics · Physics 2016-10-31 Béatrice Bonga , Brajesh Gupt , Nelson Yokomizo

We discuss the asymmetry of cosmic background evolution in time with respect to the quantum bounce in the Loop Quantum Cosmology (LQC), employing the value of scalar field at the bounce $\phi_{\rm B}$. We use the Chaotic and the $R^2$…

General Relativity and Quantum Cosmology · Physics 2019-07-03 Wen-Hsuan Lucky Chang , Jiun-Huei Proty Wu