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We consider the examples of single-field inflation models predicting large amplitudes of the curvature perturbation power spectrum at relatively small scales. It is shown that in models with an inflationary potential of double-well type the…

Astrophysics · Physics 2009-02-20 Edgar Bugaev , Peter Klimai

We use the power-counting formalism of effective field theory to study the size of loop corrections in theories of slow-roll inflation, with the aim of more precisely identifying the limits of validity of the usual classical inflationary…

High Energy Physics - Phenomenology · Physics 2009-10-17 C. P. Burgess , Hyun Min Lee , Michael Trott

A study of the slow-roll inflation for an exponential potential in the frame of the scalar-tensor theory is performed, where non-minimal kinetic coupling to curvature and non-minimal coupling of the scalar field to the Gauss-Bonnet…

High Energy Physics - Theory · Physics 2019-09-24 L. N. Granda , D. F. Jimenez

We elucidate the counting of the relevant small parameters in inflationary perturbation theory. Doing this allows for an explicit delineation of the domain of validity of the semi-classical approximation to gravity used in the calculation…

High Energy Physics - Theory · Physics 2018-02-21 Peter Adshead , C. P. Burgess , R. Holman , Sarah Shandera

Cosmic inflation, which describes an accelerated expansion of the early Universe, yields the most successful predictions regarding temperature anisotropies in the cosmic microwave background (CMB). Nevertheless, the precise origin of the…

General Relativity and Quantum Cosmology · Physics 2020-08-14 Gabriel Leon , Maria Pia Piccirilli

We study the amplification of the curvature perturbations due to a small sound speed and find that its origin is different completely from that due to the ultraslow-roll inflation. This is because when the sound speed is very small the…

General Relativity and Quantum Cosmology · Physics 2022-09-20 Rongrong Zhai , Hongwei Yu , Puxun Wu

We develop an integral form for the bispectrum in general single-field inflation whose domain of validity includes models of inflation where the background evolution is not constrained to be slowly varying everywhere. Our integral form…

Cosmology and Nongalactic Astrophysics · Physics 2018-09-18 Peter Adshead , Wayne Hu , V Miranda

[Abridged] A variety of model-dependent as well as model-independent approaches suggest that certain localized features in the primordial scalar power spectrum can lead to a significantly better fit to the observed anisotropies in the…

Cosmology and Nongalactic Astrophysics · Physics 2026-04-16 Alipriyo Hoory , Dhiraj Kumar Hazra , L. Sriramkumar

In this work we explore the power of future large-scale surveys to constrain possible deviations from the standard single-field slow-roll inflationary scenario. Specifically, we parametrize possible fluctuations around the almost…

Cosmology and Nongalactic Astrophysics · Physics 2021-05-14 Muhammad Sadegh Esmaeilian , Marzieh Farhang , Shirin Khodabakhshi

A model is developed in which the inflaton potential experiences a sudden small change in its second derivative (the effective mass of the inflaton). An exact treatment demonstrates that the resulting density perturbation has a quasi-flat…

Astrophysics · Physics 2008-12-18 Minu Joy , Varun Sahni , Alexei A. Starobinsky

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

(Shortened abstract) While a featureless, nearly scale invariant, primordial scalar power spectrum fits the most recent CMB data rather well, certain features in the spectrum are known to lead to a better fit to the data (although, the…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-30 Jerome Martin , L. Sriramkumar

We extend a previous analysis concerning cosmological fluids with generalized equations of state in order to study inflationary scenarios. In the framework of the slow-roll approximation we find the expressions for the perturbation…

Astrophysics · Physics 2009-10-28 G. Mangano , G. Miele , C. Stornaiolo

We derive the power spectrum P_\psi(k) of the gravitational waves produced during general classes of inflation with second order corrections. Using this result, we also derive the spectrum and the spectral index in the standard slow-roll…

General Relativity and Quantum Cosmology · Physics 2009-11-10 Jinn-Ouk Gong

We study non-linear contributions to the power spectrum of the curvature perturbation on super-horizon scales, produced during slow-roll inflation driven by a canonical single scalar field. We find that on large scales the linear power…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-20 Jinn-Ouk Gong , Hyerim Noh , Jai-chan Hwang

The PLANCK collaboration has determined values for the spectral parameters of the CMB radiation, namely the spectral index $n_s$, its running $\alpha_s$, the running of the running $\beta_s$, using a growing body of measurements of CMB…

General Relativity and Quantum Cosmology · Physics 2016-10-12 Jaume Amorós , Jaume de Haro

The primordial power spectra of scalar and tensor perturbations during slow-roll inflation are usually calculated with the method of Bessel function approximation. For constant-roll or ultra slow-roll inflation, the method of Bessel…

General Relativity and Quantum Cosmology · Physics 2018-04-09 Zhu Yi , Yungui Gong

The effective field theory (EFT) of inflation provides an essential picture to explore the effects of the unknown high energy physics in the single scalar field inflation models. For a generic EFT of inflation, possible high energy…

General Relativity and Quantum Cosmology · Physics 2019-12-03 Guang-Hua Ding , Jin Qiao , Qiang Wu , Tao Zhu , Anzhong Wang

The conventional slow-roll approximation is broken in the so-called "ultra slow-roll" models of inflation, for which the inflaton potential is exactly (or extremely) flat. The interesting nature of (canonical) ultra slow-roll inflation is…

Cosmology and Nongalactic Astrophysics · Physics 2016-11-18 Shin'ichi Hirano , Tsutomu Kobayashi , Shuichiro Yokoyama

We explore the correlations between correlation functions of the primordial curvature perturbation produced during inflation. We find that for general single field inflation, other than the source terms which depend on the model details,…

Cosmology and Nongalactic Astrophysics · Physics 2014-04-02 Jinn-Ouk Gong , Koenraad Schalm , Gary Shiu
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