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We adopt the double field natural inflation model motivated by the non-perturbative effects of supergravity and superstring theory to do the slow roll analysis. We show that when the parameters are suitably chosen, there exist ranges of…

General Relativity and Quantum Cosmology · Physics 2019-04-12 Ping Kwan Man Ellgan

We find multi-scalar effective field theories (EFTs) that can achieve a slow inflationary roll despite having a scalar potential that does not satisfy the usual slow-roll condition (d V)^2 << V^2/Mp^2. They evade the usual slow-roll…

High Energy Physics - Theory · Physics 2016-11-16 Peter Adshead , Diego Blas , C. P. Burgess , Peter Hayman , Subodh P Patil

We examine a wide class of multi-field inflationary models based on fields that decay or stabilize during inflation in a staggered fashion. The fields driving assisted inflation are on flat, short stretches, before they encounter a sharp…

High Energy Physics - Theory · Physics 2009-03-27 Diana Battefeld , Thorsten Battefeld

In this paper we consider the $\alpha-$attractor model and study inflation under a non-slow-roll dynamics. More precisely, we follow the approach recently proposed by Gong and Sasaki \cite{Gong:2015ypa} by means of assuming…

General Relativity and Quantum Cosmology · Physics 2016-04-05 K. Sravan Kumar , João Marto , Paulo Vargas Moniz , Suratna Das

Constant-roll warm inflation is introduced in this work. A novel approach to finding an exact solution for Friedman equations coupled to scalar field equation of motion is presented for cold inflation and is extended to warm inflation with…

General Relativity and Quantum Cosmology · Physics 2020-07-17 Vahid Kamali , Michał Artymowski , Mohammad Reza Setare

In the present work we study the consequences of considering a new family of single-field inflation models, called power-law plateau inflation, in the warm inflation framework. We consider the inflationary expansion is driven by a standard…

General Relativity and Quantum Cosmology · Physics 2017-05-24 Abdul Jawad , Nelson Videla , Faiza Gulshan

We examine inflationary universe models driven by scalar fields with logarithmic potentials of the form $V(\phi) = V_0 \phi^p(\ln \phi)^q$. Combining the slow-roll approximation with asymptotic techniques, we identify regions of the…

Astrophysics · Physics 2009-10-28 John D. Barrow , Paul Parsons

The dynamics of hybrid models is usually approximated by the evolution of a scalar field slowly rolling along a nearly flat valley. Inflation ends with a waterfall phase, due to a tachyonic instability. This final phase is usually assumed…

Cosmology and Nongalactic Astrophysics · Physics 2011-09-27 Sébastien Clesse

The linear and quadratic perturbations for a scalar-tensor model with non-minimal coupling to curvature, coupling to the Gauss-Bonnet invariant and non-minimal kinetic coupling to the Einstein tensor are developed. The quadratic action for…

General Relativity and Quantum Cosmology · Physics 2019-09-24 L. N. Granda , D. F. Jimenez

I generalize the inflationary flow equations of Hoffman and Turner to arbitrary order in slow roll. This makes it possible to study the predictions of slow roll inflation in the full observable parameter space of tensor/scalar ratio $r$,…

Astrophysics · Physics 2009-11-07 William H. Kinney

We investigate, in a model-independent way, the conditions required to obtain a satisfactory model of extended inflation in which inflation is brought to an end by a first-order phase transition. The constraints are that the correct present…

Astrophysics · Physics 2009-10-28 Anne M Green , Andrew R Liddle

We propose an extension of the Higgs inflation to the hybrid metric-Palatini gravity, where we introduce non-minimal couplings between Higgs and both the metric-type and the Palatini-type Ricci scalars. We study the inflationary…

High Energy Physics - Theory · Physics 2023-05-30 Minxi He , Yusuke Mikura , Yuichiro Tada

In this paper, we study inflation in the framework of the nonrelativistic general covariant theory of the Ho\v{r}ava-Lifshitz gravity with the projectability condition and an arbitrary coupling constant $\lambda$. We find that the…

General Relativity and Quantum Cosmology · Physics 2015-06-03 Yongqing Huang , Anzhong Wang , Qiang Wu

An appealing feature of inflationary cosmology is the presence of a phase-space attractor, "slow roll", which washes out the dependence on initial field velocities. We investigate the robustness of this property under backreaction from…

General Relativity and Quantum Cosmology · Physics 2021-04-05 Julien Grain , Vincent Vennin

We provide an update on five relatively well motivated inflationary models in which the inflaton is a Standard Model singlet scalar field. These include i) the textbook quadratic and quartic potential models but with additional couplings of…

High Energy Physics - Phenomenology · Physics 2016-04-28 Nobuchika Okada , Vedat Nefer Şenoğuz , Qaisar Shafi

The primary purpose of this study is to investigate the constant-roll inflationary scenario with anisotropic conditions concerning the Einstein-aether Scalar-tensor cosmology in noncommutative phase space. We first introduce an…

General Relativity and Quantum Cosmology · Physics 2023-02-14 Antonio Pasqua , Saeed Noori Gashti

We consider the simplest extension to the Starobinsky model, by allowing an extra scalar field to help drive inflation. We perform our analysis in the Einstein frame and calculate the power spectra at the end of inflation to second order in…

High Energy Physics - Theory · Physics 2015-10-21 Carsten van de Bruck , Laura Elena Paduraru

We find the best-fit cosmological parameters for a scenario of inflation with only the sufficient amount of accelerated expansion for the $\lambda\phi^4$ potential. While for the simplest scenario of chaotic inflation all observable…

Cosmology and Nongalactic Astrophysics · Physics 2012-06-25 Erandy Ramirez , Dominik J. Schwarz

We introduce a new class of models of chaotic inflation inspired by the superconformal approach to supergravity. This class of models allows a functional freedom of choice of the inflaton potential V = |f(\phi)|^2. The simplest model of…

High Energy Physics - Theory · Physics 2010-11-22 Renata Kallosh , Andrei Linde

Single field inflationary models are investigated within Palatini quadratic gravity represented by $R+\alpha R^2$ along with a non-minimal coupling of the form $f(\phi) R$ between the inflaton field $\phi$ and the gravity. The treatment is…

Cosmology and Nongalactic Astrophysics · Physics 2023-03-15 Mahmoud AlHallak