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In the present work we study the consequences of considering an inflationary universe model in which the Hubble rate has a quasi-exponential dependence in the inflaton field, given by $H(\phi)=H_{inf}\exp…

General Relativity and Quantum Cosmology · Physics 2017-04-05 Nelson Videla

Tachyon inflation is reconsidered by using the recent observational data obtained from Planck-2013 and BICEP2. The Hamilton-Jacobi formalism is picked out as a desirable approach in this work, which allows one to easily obtain the main…

General Relativity and Quantum Cosmology · Physics 2015-02-27 A. Aghamohammadi , A. Mohammadi , T. Golanbari , Kh. Saaidi

Hamilton-Jacobi formalism as a powerful method is being utilized to reconsider warm inflationary scenario, where the scalar field as the main component deriving inflation interacts with other field. Separating the context to strong and weak…

General Relativity and Quantum Cosmology · Physics 2017-08-08 K. Sayar , A. Mohammadi , L. Akhtari , Kh. Saaidi

We consider a type of k-inflation under the Hamilton-Jacobi approach. We calculate various observables such as the scalar power spectrum, the tensor-to-scalar ratio, the scalar spectra index for the case where the Hubble parameter is a…

General Relativity and Quantum Cosmology · Physics 2024-06-27 Rong-Jia Yang , Ming Liu

In this paper, an elegant mathematical approach is introduced to solve the equations of warm inflationary model without using extra approximations other than slow-roll. This important inflationary method known as Hamilton-Jacobian…

General Relativity and Quantum Cosmology · Physics 2020-04-08 R. Saleem , M. Zubair

In inflation with nonminimal derivative coupling there is not a conformal transformation to the Einstein frame where calculations are straightforward, and thus in order to extract inflationary observables one needs to perform a detailed and…

General Relativity and Quantum Cosmology · Physics 2016-10-14 Haidar Sheikhahmadi , Emmanuel N. Saridakis , Ali Aghamohammadi , Khaled Saaidi

In the present work we study a warm inflationary model defined by a quasi-exponential inflaton potential and an inflaton decay rate proportional to the Hubble rate. The model is characterized by three free parameters. We compute the power…

General Relativity and Quantum Cosmology · Physics 2018-06-13 Nelson Videla , Grigoris Panotopoulos

The slow-roll inflation paradigm can be systematically generalized within the framework of non-standard entropy formalisms, giving rise to a broad class of inflationary models that deviate from the conventional Bekenstein--Hawking case. We…

Cosmology and Nongalactic Astrophysics · Physics 2026-05-26 H R M Zarandi , Esmaiel Ebrahimi , Yo Toda

We use the Hamilton--Jacobi formalism to constrain the space of possible single field, inflationary Hubble flow trajectories when compared to the WMAP and Planck satellites Cosmic Microwave Background (CMB) results. This method yields…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-18 Carlo R. Contaldi , Jonathan S. Horner

Using Hamilton-Jacobi formalism, The scenario of warm inflation with viscous pressure is considered. The formalism gives a way of computing the slow-rolling parameters without extra approximation, and it is well-known as a powerful method…

Cosmology and Nongalactic Astrophysics · Physics 2017-10-17 L. Akhtari , A. Mohammadi , K. Sayar , Kh. Saaidi

We explore a square-law k-inflation using the Hamilton-Jacobi approach. Focusing on scenarios where the Hubble parameter exhibits a power-law dependence on the k-field, our analysis encompasses the computations of crucial observables, such…

General Relativity and Quantum Cosmology · Physics 2025-09-03 Ming Liu , Tong-Yu He , Bohai Chen , Zhan-Wen Han , Rong-Jia Yang

We make a more general determination of the inflationary observables in the standard 4-D and 5-D single-field inflationary scenarios, by the exact reconstruction of the dynamics of the inflation potential during the observable inflation…

Cosmology and Nongalactic Astrophysics · Physics 2009-11-10 L. A. Popa , N. Mandolesi , A. Caramete , C. Burigana

The latest CMB data from ACT DR6, combined with Planck, DESI, and BICEP/Keck, indicate a slight upward shift in the scalar spectral index, placing several previously favored inflationary models under tension. We study an inflationary…

General Relativity and Quantum Cosmology · Physics 2025-11-26 Z. Ossoulian , T. Golanbari , Kh. Saaidi

The implications of the WMAP (Wilkinson Microwave Anisotropy Probe) third year data for inflation are investigated using both the slow-roll approximation and an exact numerical integration of the inflationary power spectra including a…

Astrophysics · Physics 2009-11-11 Jerome Martin , Christophe Ringeval

Due to universality and attractor properties, $\alpha$-attractor quintessential inflation establishes direct relations between inflationary observables such as the scalar tilt $n_s$ and the tensor-to-scalar ratio $r$, and late-time dark…

Cosmology and Nongalactic Astrophysics · Physics 2024-11-26 William Giarè , Eleonora Di Valentino , Eric V. Linder , Enrico Specogna

The first year WMAP measurement of the CMB temperature anisotropy is intriguingly consistent with a larger running of the inflationary scalar spectral index than would be expected for single-field inflation. We revisit the issue of a large…

Astrophysics · Physics 2009-11-11 James M. Cline , Loison Hoi

Warm inflation in the framework of locally rotationally symmetric Bianchi type I universe model in the Hamilton-Jacobi formalism is being considered. Matter-Radiation fluid in warm inflation, endowed with and without a viscous pressure. For…

General Relativity and Quantum Cosmology · Physics 2023-10-25 M Tirandari , A Mohammadi

The recent Planck results and future releases on the horizon present a key opportunity to address a fundamental question in inflationary cosmology of whether primordial density perturbations have a quantum or thermal origin, i.e. whether…

Cosmology and Nongalactic Astrophysics · Physics 2013-06-20 Sam Bartrum , Arjun Berera , Joao G. Rosa

A generalization of the canonical and non-canonical theory of inflation is introduced in which the kinetic energy term in action is written as non-local term. The inflationary universe within the framework of considering this non-locality…

General Relativity and Quantum Cosmology · Physics 2015-07-01 Haidar Sheikhahmadi , Soheyla Ghorbani , Khaled Saaidi

In this paper we introduce the "warm vector inflation" scenario. In warm inflation scenario radiation is produced during the inflation epoch and reheating is avoided. Slow-roll and perturbation parameters of this model are presented. We…

General Relativity and Quantum Cosmology · Physics 2015-06-17 M. R. Setare , V. Kamali
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