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Modifications to the Mukhanov-Sasaki equation in loop quantum cosmology (LQC) have been phenomenologically explored using polymerization of the connection and related variables in the classical expressions in order to capture the quantum…

General Relativity and Quantum Cosmology · Physics 2024-03-06 Bao-Fei Li , Parampreet Singh

We investigate the imprints on the angular power spectra of cosmological perturbations of a pre-inflationary bounce phase, as described by the hybrid and dressed metric approaches to loop quantum cosmology. For this purpose, we derive a new…

General Relativity and Quantum Cosmology · Physics 2026-05-15 Almudena Guillén , Kai Langer , Guillermo A. Mena Marugán , Niklas Rodenbücher , Antonio Vicente-Becerril

We investigate the primordial power spectrum of cosmological tensor perturbations in the dressed metric approach to Loop Quantum Cosmology. We compute the background-dependent effective mass that affects their propagation using the…

General Relativity and Quantum Cosmology · Physics 2024-09-30 Ana Alonso-Serrano , Guillermo A. Mena Marugan , Antonio Vicente-Becerril

In Loop Quantum Cosmology, the quantization of the Hamiltonian constraint involves a regularization procedure which is affected by certain ambiguities. Moreover, different regularizations lead to distinct mathematical formulations and,…

General Relativity and Quantum Cosmology · Physics 2025-03-21 Maciej Kowalczyk , Guillermo A. Mena Marugán , Tomasz Pawłowski

We study the effect on the primordial tensor power spectrum of varying the number of e-folds during slow-roll inflation in Loop Quantum Cosmology with a Starobinsky potential. Using the hybrid quantization approach, we derive the effective…

General Relativity and Quantum Cosmology · Physics 2025-11-20 Marceau Henry , Guillermo A. Mena Marugán , Antonio Vicente-Becerril

A model-independent determination of the primordial power spectrum of matter density fluctuations could uniquely probe physics of the very early universe, and provide powerful constraints on inflationary models. We parametrize the…

Astrophysics · Physics 2009-10-31 Yun Wang , Grant J. Mathews

We perform a cosmological analysis in which we allow the primordial power spectrum of scalar perturbations to assume a shape that is different with respect to the usual power-law, arising from the simplest models of cosmological inflation.…

Cosmology and Nongalactic Astrophysics · Physics 2016-06-22 Stefano Gariazzo

Loop quantum cosmology tries to capture the main ideas of loop quantum gravity and to apply them to the Universe as a whole. Two main approaches within this framework have been considered to date for the study of cosmological perturbations:…

General Relativity and Quantum Cosmology · Physics 2015-10-08 B. Bolliet , J. Grain , C. Stahl , L. Linsefors , A. Barrau

We reconstruct the shape of the primordial power spectrum from the latest cosmic microwave background data, including the new results from the Wilkinson Microwave Anisotropy Probe (WMAP), and large scale structure data from the two degree…

Astrophysics · Physics 2009-11-07 S. L. Bridle , A. M. Lewis , J. Weller , G. Efstathiou

The dressed metric and the hybrid approach to perturbations are the two main approaches to capture the effects of quantum geometry in the primordial power spectrum in loop quantum cosmology. Both consider Fock quantized perturbations over a…

General Relativity and Quantum Cosmology · Physics 2022-06-28 Bao-Fei Li , Parampreet Singh

We compare the primordial scalar power spectra in the loop cosmological models using the effective dynamics of the hybrid approach to cosmological perturbations in which the background is loop quantized but the perturbations are Fock…

General Relativity and Quantum Cosmology · Physics 2021-01-04 Bao-Fei Li , Javier Olmedo , Parampreet Singh , Anzhong Wang

We compute the predictions for the power spectrum of scalar perturbations from a recent new proposal for the effective Hamiltonian of loop quantum cosmology. The model provides an attractive picture of the early cosmos, in which our…

General Relativity and Quantum Cosmology · Physics 2018-07-06 Ivan Agullo

Pursuing the original idea proposed in our previous paper (Paper I), we improve the method to determine the shape of the initial curvature perturbation spectrum $P(k)$ from the CMB data. The thickness of the last scattering surface (LSS)…

Astrophysics · Physics 2009-10-09 Makoto Matsumiya , Misao Sasaki , Jun'ichi Yokoyama

With the recent publication of the measurements of the radiation angular power spectrum from the BOOMERanG Antarctic flight (de Bernardis et al. 2000), it has become apparent that the currently favoured spatially-flat cold dark matter model…

Astrophysics · Physics 2009-10-31 Louise M. Griffiths , Joseph Silk , Saleem Zaroubi

We provide the power spectrum of small scalar perturbations propagating in an inflationary scenario within loop quantum cosmology. We consider the hybrid quantization approach applied to a Friedmann--Robertson--Walker spacetime with flat…

General Relativity and Quantum Cosmology · Physics 2016-06-22 Daniel Martín de Blas , Javier Olmedo

In a previous paper (part I), the mathematical properties of the cosmic microwave background radiation power spectrum which presents oscillations were discussed. Here, we discuss the physical interpretation: a power spectrum with…

Cosmology and Nongalactic Astrophysics · Physics 2014-01-28 Martin Lopez-Corredoira

The two point angular correlation function is an excellent measure of structure in the universe. To extract from it the three dimensional power spectrum, one must invert Limber's Equation. Here we perform this inversion using a Bayesian…

Astrophysics · Physics 2008-11-26 Scott Dodelson , Enrique Gaztanaga

In order to investigate the potential observational signals of different regularization ambiguities in loop quantum cosmological models, we systematically compute and compare the primordial scalar power spectra and the resulting angular…

General Relativity and Quantum Cosmology · Physics 2024-08-30 Bao-Fei Li , Meysam Motaharfar , Parampreet Singh

Together with holonomy corrections, inverse volume terms should be taken into account when studying the primordial universe in loop quantum cosmology. We investigate how the tensor power spectrum is modified with respect to the standard…

General Relativity and Quantum Cosmology · Physics 2013-05-29 J. Grain , A. Barrau , A. Gorecki

Three peaks and two dips have been detected in the power spectrum of the cosmic microwave background from the BOOMERANG experiment, at $\ell \sim 210, 540, 840$ and $\ell \sim 420, 750$, respectively. Using model-independent analyses, we…

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