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Certain anomalies in the CMB bring out a tension between the six-parameter flat $\Lambda$CDM model and the CMB data. We revisit the PLANCK analysis with loop quantum cosmology (LQC) predictions and show that LQC alleviates both the…

Cosmology and Nongalactic Astrophysics · Physics 2020-08-05 Abhay Ashtekar , Brajesh Gupt , Donghui Jeong , V. Sreenath

In this Essay we investigate the observational signatures of Loop Quantum Cosmology (LQC) in the CMB data. First, we concentrate on the dynamics of LQC and we provide the basic cosmological functions. We then obtain the power spectrum of…

General Relativity and Quantum Cosmology · Physics 2017-11-22 Spyros Basilakos , Vahid Kamali , Ahmad Mehrabi

We explore a model of the early universe in which the inflationary epoch is preceded by a cosmic bounce, and argue that this scenario provides a common origin to several of the anomalous features that have been observed at large angular…

Cosmology and Nongalactic Astrophysics · Physics 2021-02-17 Ivan Agullo , Dimitrios Kranas , V. Sreenath

We provide an exhaustive numerical exploration of the predictions of loop quantum cosmology (LQC) with a post-bounce phase of inflation for the primordial power spectrum of scalar and tensor perturbations. We extend previous analysis by…

General Relativity and Quantum Cosmology · Physics 2015-12-30 Ivan Agullo , Noah A. Morris

In this paper we consider realistic model of inflation embedded in the framework of loop quantum cosmology. Phase of inflation is preceded here by the phase of a quantum bounce. We show how parameters of inflation depend on the initial…

General Relativity and Quantum Cosmology · Physics 2010-04-06 Jakub Mielczarek

We argue that the anomalous power asymmetry observed in the cosmic microwave background (CMB) may have originated in a cosmic bounce preceding inflation. In loop quantum cosmology (LQC) the big bang singularity is generically replaced by a…

General Relativity and Quantum Cosmology · Physics 2015-09-30 Ivan Agullo

The standard model of cosmology assumes a homogeneous and isotropic universe that undergoes a period of exponential expansion very early on, named inflation. This stretches quantum fluctuations from the onset of inflation to cosmological…

General Relativity and Quantum Cosmology · Physics 2024-10-22 Rita B. Neves

The lack of correlations at the long-wavelength scales of the cosmic microwave background spectrum is a long-standing puzzle and it persists in the latest Planck data. By considering the Hartle-Hawking no-boundary wave function as the…

General Relativity and Quantum Cosmology · Physics 2018-11-22 Pisin Chen , Yu-Hsiang Lin , Dong-han Yeom

We investigate the ability to constrain oscillatory features in the primordial power spectrum using current and future cosmic microwave background observations. In particular, we study the observability of an oscillation arising from…

Astrophysics · Physics 2011-05-12 Takemi Okamoto , Eugene A. Lim

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 an inflationary model of the universe based on the assumption that space-time is noncommutative in the very early universe. We analyze the effects of space-time noncommutativity on the quantum fluctuations of an inflaton…

High Energy Physics - Theory · Physics 2010-04-05 Masafumi Fukuma , Yuji Kono , Akitsugu Miwa

Primordial power spectra with low power at long wavelengths can alleviate lensing anomaly. However the extent to which data favours such a primordial spectra is not clear. In this work, we investigate power suppression and related…

Cosmology and Nongalactic Astrophysics · Physics 2026-02-03 Roshna K , V. Sreenath

Suppression in primordial power on the Universe's largest observable scales has been invoked as a possible explanation for large-angle observations in the cosmic microwave background, and is allowed or predicted by some inflationary models.…

Cosmology and Nongalactic Astrophysics · Physics 2011-04-04 Cameron Gibelyou , Dragan Huterer , Wenjuan Fang

Bouncing models of cosmology, as they arise e.g. in loop quantum cosmology, can be followed by an inflationary phase and generate close-to-scale-invariant fluctuation spectra as observed in the Cosmic Microwave Background (CMB). However,…

Cosmology and Nongalactic Astrophysics · Physics 2023-05-12 Bartjan van Tent , Paola C. M. Delgado , Ruth Durrer

Noncommutative geometry can provide effective description of physics at very short distances taking into account generic effects of quantum gravity. Inflation amplifies tiny quantum fluctuations in the early universe to macroscopic scales…

Cosmology and Nongalactic Astrophysics · Physics 2011-03-18 Tomi S. Koivisto , David F. Mota

Primordial non-Gaussianity has set strong constraints on models of the early universe. Studies have shown that Loop Quantum Cosmology (LQC), which is an attempt to extend inflationary scenario to planck scales, leads to a strongly scale…

Cosmology and Nongalactic Astrophysics · Physics 2023-08-16 Roshna K , V. Sreenath

Loop quantum cosmology (LQC) provides a resolution of the classical big bang singularity in the deep Planck era. The evolution, prior to the usual slow-roll inflation, naturally generates excited states at the onset of the slow-roll…

Cosmology and Nongalactic Astrophysics · Physics 2018-02-07 Tao Zhu , Anzhong Wang , Klaus Kirsten , Gerald Cleaver , Qin Sheng

We revisit the Cosmic Microwave Background (CMB) constraints on the spatial curvature of the Universe, assessing how they change when the curvature parameter and the primordial inflationary scalar spectrum are treated consistently within…

Cosmology and Nongalactic Astrophysics · Physics 2025-10-01 Enrico Specogna , Tatevik Vardanyan , William Giarè , Eleonora Di Valentino

This work is an analytical study of the main differences between classical inflationary effects of a fast-roll regime and imprints of hybrid Loop Quantum Cosmology (LQC) on the primordial power spectrum. Effective LQC solutions of…

General Relativity and Quantum Cosmology · Physics 2021-10-01 Beatriz Elizaga Navascués , Guillermo A. Mena Marugán

We assess two potential signals of the formation of our universe by the decay of a false vacuum. Negative spatial curvature is one possibility, but the window for its detection is now small. However, another possible signal is a suppression…

High Energy Physics - Theory · Physics 2015-04-29 Raphael Bousso , Daniel Harlow , Leonardo Senatore
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