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We analyze a class of generalized inflationary models proposed in Ref. [1], known as $\beta$-exponential inflation. We show that this kind of potential can arise in the context of brane cosmology, where the field describing the size of the…

Cosmology and Nongalactic Astrophysics · Physics 2018-03-15 M. A. Santos , M. Benetti , J. S. Alcaniz , F. A. Brito , R. Silva

The Hamiltonian approach to cosmological perturbations in general relativity in finite space-time is developed, where a cosmological scale factor is identified with spatial averaging the metric determinant logarithm. This identification…

High Energy Physics - Theory · Physics 2009-11-11 B. M. Barbashov , V. N. Pervushin , A. F. Zakharov , V. A. Zinchuk

Given the persistence of various tensions in the "Cosmic Concordance" -- such as the "Hubble Tension", and possible departures from LambdaCDM time evolution -- seen from combinations of complementary data sets (e.g., Cosmic Microwave…

Cosmology and Nongalactic Astrophysics · Physics 2026-02-19 Brett Bochner , Aiden Jin

We introduce the cosmic holographic bounds with two UV and IR cutoff scales, to deal with both the inflationary universe in the past and dark energy in the future. To describe quantum fluctuations of inflation on sub-horizon scales, we use…

High Energy Physics - Theory · Physics 2009-11-11 Yun Soo Myung

A major outstanding challenge in cosmology is the persistent discrepancy between the Hubble constant obtained from early and late universe measurements -- the Hubble tension. Examining cosmological evolution through the lens of information…

Cosmology and Nongalactic Astrophysics · Physics 2025-03-26 Juan Luis Cabrera Fernández

The Hubble crisis is the discrepancy in the values of the Hubble constant inferred from diverse observations in the late and early Universe, being of the order 5$\sigma$. Instead of resolution, the conflict is getting larger with further…

Cosmology and Nongalactic Astrophysics · Physics 2025-04-29 Furkan Şakir Dilsiz , Cemsinan Deliduman , Selinay Sude Binici

Future precision measurements of CMB polarizations can shed new light on the problem so called Hubble tension. The Hubble tension comes from the difference of the evolutions of the Hubble parameter which are determined with two different…

Cosmology and Nongalactic Astrophysics · Physics 2021-01-15 Noriaki Kitazawa

We propose a revised formulation of General Relativity for cosmological settings, in which the Einstein constant varies with the energy density of the Universe. We demonstrate that this modification has only phenomenological impact of…

General Relativity and Quantum Cosmology · Physics 2025-08-28 Giovanni Montani , Giulia Maniccia , Elisa Fazzari , Alessandro Melchiorri

We analyze how predictions of cosmological models depend on a choice of described observational data, restrictions on flatness, and how this choice can alleviate the $H_0$ tension. These effects are demonstrated in the $w$CDM model in…

General Relativity and Quantum Cosmology · Physics 2020-02-11 G. S. Sharov , E. S. Sinyakov

We are at an interesting juncture in cosmology. With new methods and technology, the accuracy in measurement of the Hubble constant has vastly improved, but a recent tension has arisen that is either signaling new physics or as-yet…

Cosmology and Nongalactic Astrophysics · Physics 2017-06-12 Wendy L. Freedman

Local measurements of the Hubble parameter are increasingly in tension with the value inferred from a $\Lambda$CDM fit to the cosmic microwave background (CMB) data. In this paper, we construct scenarios in which evolving scalar fields…

Cosmology and Nongalactic Astrophysics · Physics 2023-10-13 Prateek Agrawal , Francis-Yan Cyr-Racine , David Pinner , Lisa Randall

We show how a modified Friedmann equation, originating from a model of the universe built from a certain $W_3$ algebra, has the potential to explain the difference between the Hubble constants extracted from CMB data and from supernova…

General Relativity and Quantum Cosmology · Physics 2022-05-11 J. Ambjorn , Y. Watabiki

We discuss cosmology based on a Cuscuta-Galileon gravity theory, which preserves just two degrees of freedom. Although there exists no additional degrees of freedom, introduction of a potential of a scalar field changes the dynamics. The…

General Relativity and Quantum Cosmology · Physics 2022-05-17 Kei-ichi Maeda , Sirachak Panpanich

A way to address the conundrum of Quantum Gravity is to illustrate the potentially fundamental interplay between quantum field theory, curved space-times physics and thermodynamics. So far, when studying moving quantum systems in the…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Nathaniel Obadia

The standard cosmological model, known as the LambdaCDM model, has been successful in many respects, but it has some significant discrepancies, some of which have not been resolved yet. In measuring the Hubble-Lematre parameter, there is an…

General Relativity and Quantum Cosmology · Physics 2024-07-10 Kourosh Nozari , Sara Saghafi , Milad Hajebrahimi

We consider the inflation produced by two coupled fluids in the flat Friedmann-Robertson-Walker universe. Different cosmological models for describing inflation by use of an inhomogeneous equation of state for the fluid are investigated.…

General Relativity and Quantum Cosmology · Physics 2016-05-12 I. Brevik , A. V. Timoshkin

Differences in the values of the Hubble constant obtained from the local universe and the early universe have resulted in a significant tension. This tension signifies that our understanding of cosmology (physical processes and/or…

Cosmology and Nongalactic Astrophysics · Physics 2025-07-22 Gawain Simpson , Krzysztof Bolejko , Stephen Walters

Previously defined covariant and gauge-invariant perturbation variables, representing, e.g., the fractional spatial energy density gradient on hypersurfaces of constant expansion, are used to simplify the linear perturbation analysis of a…

Astrophysics · Physics 2009-10-30 Winfried Zimdahl

Vacuum energy, a prediction of quantum field theory, manifests itself as a cosmological constant in general relativity. In this Letter, we propose a novel inflationary scenario driven by a bare cosmological constant $\Lambda$, which…

General Relativity and Quantum Cosmology · Physics 2026-03-25 Chengsheng Mu , Shuxun Tian , Shuo Cao , Zong-Hong Zhu

A huge value of cosmological constant characteristic for the particle physics and the inflation of early Universe are inherently related to each other: one can construct a fine-tuned superpotential, which produces a flat potential of…

General Relativity and Quantum Cosmology · Physics 2015-06-03 V. V. Kiselev , S. A. Timofeev