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We study the power spectrum of the mass density perturbations in an inflation scenario that includes thermal dissipation. We show that the condition on which the thermal fluctuations dominate the primordial density perturbations can easily…

Astrophysics · Physics 2009-10-31 Wolung Lee , Li-Zhi Fang

We investigate the observational constraints on the modified gravity, which combines the $R^{2-q}$ inflation with the power-law (exponential) type of the viable $f(R)$ dark energy models. We discuss the difference between the combined model…

Cosmology and Nongalactic Astrophysics · Physics 2015-10-27 Chao-Qiang Geng , Chung-Chi Lee , Shan Lin

In this work, we study the effects on the relevant observational parameters of an inflationary universe from a chaotic potential with a step. We numerically evolve the perturbation equations within both cold inflation and warm inflation. On…

General Relativity and Quantum Cosmology · Physics 2023-03-09 Clara Rojas , Rafael Hernández-Jiménez

Constraints to the parameters of inflation models are often derived assuming some plausible range for the number--e.g., $N_k=46$ to $N_k=60$--of $e$-folds of inflation that occurred between the time that our current observable Universe…

Cosmology and Nongalactic Astrophysics · Physics 2016-08-08 Julian B. Munoz , Marc Kamionkowski

Recently, it has been realized that the so-called G-inflation model inspired by supplementing a generalized covariant Galileon-like non-linear derivative self-interacting term to the standard kinetic term should be ruled out from…

General Relativity and Quantum Cosmology · Physics 2017-12-06 Maysam Motaharfar , Erfan Massaeli , Hamid Reza Sepangi

Quantum gravity computations suggest the existence of an ultraviolet and an infrared fixed point where quantum scale invariance emerges as an exact symmetry. We discuss a particular variable gravity model for the crossover between these…

General Relativity and Quantum Cosmology · Physics 2017-09-20 Javier Rubio , Christof Wetterich

We study a general form for the dissipative coefficient $\Gamma(T,\phi)=C_\phi\,T^{m}/\phi^{m-1}$ in the context of warm intermediate and logamediate inflationary universe models. We analyze these models in the weak and strong dissipative…

General Relativity and Quantum Cosmology · Physics 2014-04-14 Ramon Herrera , Marco Olivares , Nelson Videla

We investigate the ability of current CMB data to reliably constrain the form of the primordial power spectrum generated during inflation. We attempt to identify more exotic power spectra that yield equally good fits to the data as simple…

Astrophysics · Physics 2009-06-23 Brian A. Powell , William H. Kinney

We show that warm inflation can be successfully realized in the high temperature regime through dissipative interactions between the inflaton and a single fermionic degree of freedom, provided that the latter's mass is an oscillatory…

High Energy Physics - Phenomenology · Physics 2023-08-02 Paulo B. Ferraz , João G. Rosa

We show that, for a given fixed value of the number of e-folds of the homogeneous solution, inflation succeeds with order unity inhomogeneities in the initial conditions above a characteristic value of the tensor-to-scalar ratio $r$. In…

Cosmology and Nongalactic Astrophysics · Physics 2025-12-16 Panagiotis Giannadakis , Matthew Elley , Raphael Flauger , Eugene A. Lim

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

Decoupling of heavy modes in effective low energy theory is one of the most fundamental concepts in physics. It tells us that modes must have a negligible effect on the physics of gravitational backgrounds with curvature radius larger than…

High Energy Physics - Theory · Physics 2020-05-12 Gia Dvali , Alex Kehagias , Antonio Riotto

Picking out DBI scalar field as inflation, the slow-rolling inflationary scenario is studied by attributing an exponential time function to scale factor; known as intermediate inflation. The perturbation parameters of the model are…

General Relativity and Quantum Cosmology · Physics 2017-08-15 N. Nazavari , A. Mohammadi , Z. Ossoulian , Kh. Saaidi

The angular power spectrum is investigated in the model of supergravity, incorporating the target-space duality and the non-perturbative gaugino condensation in the hidden sector. The inflation and supersymmetry breaking occur at once by…

High Energy Physics - Phenomenology · Physics 2007-05-23 Mitsuo J. Hayashi , Shiro Hirai , Yusuke Okame , Tomoki Watanabe

In this paper, we propose a new method to calculate the mode functions in the noncommutative power-law inflation model. In this model, all the modes created when the stringy space-time uncertainty relation is satisfied are generated inside…

Cosmology and Nongalactic Astrophysics · Physics 2014-04-02 Chao-Jun Feng , Xin-Zhou Li , Dao-Jun Liu

Recent BICEP/Keck data on the cosmic microwave background, in combination with previous WMAP and Planck data, impose strong new constraints on the tilt in the scalar perturbation spectrum, $n_s$, as well as the tensor-to-scalar ratio, $r$.…

High Energy Physics - Phenomenology · Physics 2022-02-16 John Ellis , Marcos A. G. Garcia , Dimitri V. Nanopoulos , Keith A. Olive , Sarunas Verner

Multi-natural inflation is studied in the context of warm inflation. We study the warm multi-natural inflation scenario with both linear and cubic temperature-dependent dissipation coefficients. The model is motivated by axion-like…

High Energy Physics - Phenomenology · Physics 2025-09-01 Asuka Ito , Rudnei O. Ramos

In the present work, we study the consequences of considering a recently proposed polynomial inflationary potential in the context of the generalized, modified, and generalized cosmic Chaplygin gas models. In addition, we consider…

General Relativity and Quantum Cosmology · Physics 2018-01-17 Abdul Jawad , Shahid Chaudhary , Nelson Videla

Thermal inflation, a brief low energy inflation after the primordial inflation, resolves the moduli problem in the context of supersymmetric cosmology. In the thermal inflation scenario, the primordial power spectrum is modestly redshifted…

Cosmology and Nongalactic Astrophysics · Physics 2020-02-14 Heeseung Zoe

In the present work we show that warm chaotic inflation characterized by a simple $\frac{\lambda}{4}\phi^{4}$ self-interaction potential for the inflaton, excluded by current data in standard cold inflation, and by an inflaton decay rate…

General Relativity and Quantum Cosmology · Physics 2015-10-26 Grigorios Panotopoulos , Nelson Videla