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Observational missions have provided us with a reliable model of the evolution of the universe starting from the last scattering surface all the way to future infinity. Furthermore given a specific model of inflation, using quantum field…

General Relativity and Quantum Cosmology · Physics 2017-01-19 Abhay Ashtekar , Brajesh Gupt

In this work, we propose a new model that combines holographic dark energy with modified gravity $f(Q,T)$ to explore a possible explanation for the accelerated expansion of the universe. Since there are several tensions of cosmological…

Cosmology and Nongalactic Astrophysics · Physics 2025-07-08 Xuwei Zhang , Xiaofeng Yang , Yunliang Ren , Shuangnan Chen , Yangjun Shi , Cheng Cheng , Xiaolong He

In this paper, inflationary cosmology is reviewed, paying particular attention to its observational signatures associated with large-scale density perturbations generated from quantum fluctuations. In the most general scalar-tensor theories…

Cosmology and Nongalactic Astrophysics · Physics 2014-06-13 Shinji Tsujikawa

We propose the holographic principle as a dynamical cutoff for any quantum theory of gravity with a geometric description at low energies, incorporating ideas of effective field theory. We illustrate the proposal by revisiting the problem…

High Energy Physics - Theory · Physics 2014-06-20 Fábio Novaes , Bruno Carneiro da Cunha

The theory of inflation provides an elegant explanation for the nearly flat universe observed today, which represents one of the pillars of the standard cosmological model. However, recent studies have reported some deviations from a flat…

Cosmology and Nongalactic Astrophysics · Physics 2024-04-25 Matteo Califano , Rocco D'Agostino , Daniele Vernieri

We propose a new four-parameter entropy function that generalizes the Tsallis, R\'{e}nyi, Barrow, Sharma-Mittal, Kaniadakis and Loop Quantum Gravity entropies for suitable limits of the parameters. Consequently, we address the early and…

General Relativity and Quantum Cosmology · Physics 2022-06-15 Shin'ichi Nojiri , Sergei D. Odintsov , Tanmoy Paul

Advances in our understanding of the origin, evolution and structure of the universe have long been driven by cosmological perturbation theory, model building and effective field theory. In this review, we introduce numerical relativity as…

General Relativity and Quantum Cosmology · Physics 2022-03-08 Anna Ijjas

The Weyl-Wigner-Groenewold-Moyal formalism of deformation quantization is applied to the closed Friedmann-Lema\^itre-Robertson-Walker (FLRW) cosmological model. We show that the phase space average for the surface of the apparent horizon is…

General Relativity and Quantum Cosmology · Physics 2015-02-26 M. Rashki , S. Jalalzadeh

An effective theory based on wave optics is used to describe indeterminacy of position in holographic spacetime with a UV cutoff at the Planck scale. Wavefunctions describing spacetime positions are modeled as complex disturbances of…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Craig J. Hogan

In this paper we find a solution for a quasi-isotropic inflationary Universe which allows to introduce in the problem a certain degree of inhomogeneity. We consider a model which generalize the (flat) FRW one by introducing a first order…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Giovanni Paolo Imponente , Giovanni Montani

With future galaxy surveys, a huge number of Fourier modes of the distribution of the large scale structures in the Universe will become available. These modes are complementary to those of the CMB and can be used to set constraints on…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-20 Zhiqi Huang , Licia Verde , Filippo Vernizzi

In light of the recent observational data coming from the sky we have two significant directions in the field of theoretical cosmology recently. First, we are now able to make use of present observations, such as the Planck and BICEP2 data,…

High Energy Physics - Theory · Physics 2014-06-19 Yi-Fu Cai

We present an explicit formulation of cosmological perturbation theory for three-field models with a flat field space. By performing rotations to align one field with the direction of curvature perturbations and applying the same rotations…

High Energy Physics - Theory · Physics 2026-01-28 Amjad Ashoorioon , Shinji Mukohyama , Kazem Rezazadeh , Navid Talebizadeh

This review article aims at presenting the theory of inflation. We first describe the background spacetime behavior during the slow-roll phase and analyze how inflation ends and the Universe reheats. Then, we present the theory of…

High Energy Physics - Theory · Physics 2009-11-10 Jerome Martin

It is often argued that inflation erases all the information about what took place before it started. Quantum gravity, relevant in the Planck era, seems therefore mostly impossible to probe with cosmological observations. In general, only…

General Relativity and Quantum Cosmology · Physics 2016-06-15 Boris Bolliet , Aurelien Barrau , Julien Grain , Susanne Schander

Models of cosmic inflation suggest that our universe underwent an early phase of accelerated expansion, driven by the dynamics of one or more scalar fields. Inflationary models make specific, quantitative predictions for several observable…

Cosmology and Nongalactic Astrophysics · Physics 2016-05-10 David I. Kaiser

Inflationary cosmology represents a well-studied framework to describe the expansion of space in the early universe, as it explains the origin of the large-scale structure of the cosmos and the isotropy of the cosmic microwave background…

Cosmology and Nongalactic Astrophysics · Physics 2019-07-16 I. G. Marian , N. Defenu , U. D. Jentschura , A. Trombettoni , I. Nandori

We interpret the Holographic Conjecture in terms of quantum bits (qubits). N-qubit states are associated with surfaces that are punctured in N points by spin networks' edges labeled by the spin-1/2 representation of SU(2), which are in a…

General Relativity and Quantum Cosmology · Physics 2015-06-25 P. A. Zizzi

Observational Cosmology has indeed made very rapid progress in recent years. The ability to quantify the universe has largely improved due to observational constraints coming from structure formation Measurements of CMB anisotropy and, more…

Astrophysics · Physics 2009-11-11 Tarun Souradeep

In this paper we propose a novel unified cosmological model that connects a pre-inflationary epoch, starting at the Planckian time, with the onset of inflation within a single scalar-field framework. The pre-inflationary phase is…

General Relativity and Quantum Cosmology · Physics 2026-05-20 M. Montes , José Edgar Madriz Aguilar , A. Bernal , Diego Allan Reyna
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