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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

We study analytically and numerically the inflationary solutions for various type scalar potentials in the nonminimally coupled scalar field theory. The Hamilton-Jacobi equation is used to deal with nonlinear evolutions of inhomogeneous…

Astrophysics · Physics 2009-11-11 Seoktae Koh , Sang Pyo Kim , Doo Jong Song

The Hamilton-Jacobi approach is a powerful tool to describe super-Hubble dynamics during cosmological inflation in a non-linear way. A key assumption of this framework is to neglect anisotropic perturbations on large scales. We show that…

Cosmology and Nongalactic Astrophysics · Physics 2025-08-15 Danilo Artigas , Emmanuel Frion , Tays Miranda , Vincent Vennin , David Wands

I describe a general approach to characterizing cosmological inflation outside the standard slow-roll approximation, based on the Hamilton-Jacobi formulation of scalar field dynamics. The basic idea is to view the equation of state of the…

High Energy Physics - Phenomenology · Physics 2016-08-24 William H. Kinney

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

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

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

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

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 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

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

In this work, we investigate the Hamilton-Jacobi formalism for non-minimally coupled inflation, focusing on the methodological frame-dependence arising from its application in the Jordan and Einstein frames. We systematically compare the…

General Relativity and Quantum Cosmology · Physics 2025-11-06 Feng-Yi Zhang , Li-Yang Chen , Rongrong Zhai

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

Slow-roll inflationary scenario is considered in non-canonical scalar field model supposing a power-law function for kinetic term, and using two formalisms. In the first approach, the potential is considered as a power-law function, that is…

General Relativity and Quantum Cosmology · Physics 2017-08-15 Kh. Saaidi , A. Mohammadi , T. Golanbari

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

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 study the dynamics of a generalized inflationary model in which both the scalar field and its derivatives are coupled to the gravity. We consider a general form of the nonminimal derivative coupling in order to have a complete treatment…

Cosmology and Nongalactic Astrophysics · Physics 2016-10-06 Kourosh Nozari , Narges Rashidi

This paper revisits the Inflationary scenario within the framework of scalar field models possessing a non-canonical kinetic term. We obtain closed form solutions for all essential quantities associated with chaotic inflation including slow…

Cosmology and Nongalactic Astrophysics · Physics 2012-10-03 Sanil Unnikrishnan , Varun Sahni , Aleksey Toporensky

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

Slow roll reconstruction is derived from the Hamilton-Jacobi formulation of inflationary dynamics. It automatically includes information from sub-leading terms in slow roll, and facilitatesthe inclusion of priors based on the duration on…

Astrophysics · Physics 2009-06-23 Peter Adshead , Richard Easther
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