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We perform a model-independent analysis of kinetically driven inflation (KDI) which (partially) includes Generalized G-inflation and Ghost inflation. We evaluate the background evolution splitting into the inflationary attractor and the…

High Energy Physics - Theory · Physics 2018-04-25 Rio Saitou

We discuss an inflation model, in which the inflation is driven by a single scalar field with exponential potential on a warped DGP brane. In contrast to the power law inflation in standard model, we find that the inflationary phase can…

High Energy Physics - Theory · Physics 2009-11-10 Rong-Gen Cai , Hongsheng Zhang

The constant-roll inflation with small positive value of the constant-roll parameter $\beta\equiv \frac{\ddot\phi}{H\dot\phi}={\rm const.}$ has been known to produce a slightly red-tilted curvature power spectrum compatible with the current…

General Relativity and Quantum Cosmology · Physics 2020-04-21 Hayato Motohashi , Shinji Mukohyama , Michele Oliosi

Inflation predicts the generation of cosmological perturbations. Usually, the power spectra for the scalar and tensor modes are calculated with help of the slow roll approximation. In the case of power law inflation an exact result is…

Astrophysics · Physics 2007-05-23 Dominik J. Schwarz , Jerome Martin

Generalized slow roll conditions and parameters are obtained for a general form of scalar-tensor theory (with no external sources), having arbitrary functions describing a nonminimal gravitational coupling F(\phi), a Kahler-like kinetic…

General Relativity and Quantum Cosmology · Physics 2009-11-07 J. R. Morris

We analyze the spectrum of density perturbations generated in models of the recently discovered "D-cceleration" mechanism of inflation. In this scenario, strong coupling quantum field theoretic effects sum to provide a DBI-like action for…

High Energy Physics - Theory · Physics 2009-11-10 Mohsen Alishahiha , Eva Silverstein , David Tong

In this paper we investigate the implications of having a varying second slow-roll index on the canonical scalar field inflationary dynamics. We shall be interested in cases that the second slow-roll can take small values and…

General Relativity and Quantum Cosmology · Physics 2017-05-03 S. D. Odintsov , V. K. Oikonomou

Many statistics available to constrain non-Gaussianity from inflation are simplest to use under the assumption that the curvature correlation functions are hierarchical. That is, if the n-point function is proportional to the (n-1) power of…

Astrophysics · Physics 2010-04-30 Sarah Shandera

In models of cosmological inflation motivated by dynamical supersymmetry breaking, the potential driving inflation may be characterized by inverse powers of a scalar field. These models produce observables similar to those typical of the…

High Energy Physics - Phenomenology · Physics 2009-10-31 William H. Kinney , Antonio Riotto

The eta problem is one of the most significant obstacles to building a successful inflationary model in string theory. Planck mass suppressed corrections to the inflaton potential generally lead to inflaton masses of order the Hubble scale…

High Energy Physics - Theory · Physics 2010-01-15 Damien A. Easson , Ruth Gregory

Slow-roll of the inflaton field defines the standard dynamics of the inflationary epoch. However, the inflationary system deviates from slow-roll when it encounters an extremely flat region of the inflaton potential, and enters a phase…

Cosmology and Nongalactic Astrophysics · Physics 2024-01-04 Sandip Biswas , Kaushik Bhattacharya , Suratna Das

Stochastic inflation, together with the $\Delta N$ formalism, provides a powerful tool for estimating the large-scale behaviour of primordial fluctuations. In this work, we develop a numerical code to capture the non-perturbative statistics…

Cosmology and Nongalactic Astrophysics · Physics 2025-03-10 Devanshu Sharma

Loop quantum cosmology is a symmetry-reduced application of loop quantum gravity. The theory predicts a bounce for the universe at the Planck scale and resolves the singularity of standard cosmology. The dynamics is also governed by an…

General Relativity and Quantum Cosmology · Physics 2024-06-27 Abolhassan Mohammadi

We examine the regime of validity of $N$-point spectra predictions of single field inflation models that invoke transient periods of non-adiabatic evolution. Such models generate oscillatory features in these spectra spanning frequencies up…

Cosmology and Nongalactic Astrophysics · Physics 2014-04-30 Peter Adshead , Wayne Hu

For a single scalar field with unit sound speed minimally coupled to Einstein gravity, there are exactly three distinct cosmological solutions which produce a scale invariant spectrum of curvature perturbations in a dynamical attractor…

High Energy Physics - Theory · Physics 2012-01-05 Austin Joyce , Justin Khoury

In this work, we systematically present a new dynamical systems approach to standard inflationary processes and their variants as constant-roll inflation. Using the techniques presented in our work one can in general investigate the…

General Relativity and Quantum Cosmology · Physics 2026-01-13 Sandip Biswas , Saddam Hussain , Kaushik Bhattacharya

It is shown that a large class of higher-order (i.e. non-quadratic) scalar kinetic terms can, without the help of potential terms, drive an inflationary evolution starting from rather generic initial conditions. In many models, this…

High Energy Physics - Theory · Physics 2008-11-26 C. Armendariz-Picon , T. Damour , V. Mukhanov

Braneworld inflation on the resolved warped deformed conifold is represented by the dynamics of a D3-brane probe with the world volume of a brane spanning the large dimensions of the observable Universe. This model was recently proposed as…

High Energy Physics - Theory · Physics 2008-11-26 Alex Buchel

In Brans-Dicke theory the Universe becomes divided after inflation into many exponentially large domains with different values of the effective gravitational constant. Such a process can be described by diffusion equations for the…

General Relativity and Quantum Cosmology · Physics 2009-09-29 Juan Garcia-Bellido , Andrei Linde

The scenario of constant-roll inflation in the frame of the RSII brane gravity model is considered. Based on the scenario, the smallness of the second slow-roll parameter is released and it is assumed as a constant which could be of the…

General Relativity and Quantum Cosmology · Physics 2020-07-08 Abolhassan Mohammadi , Tayeb Golanbari , Salah Nasri , Khaled Saaidi