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We present and discuss a new approach increasing by orders of magnitude the speed of performing Bayesian inference and parameter estimation within the framework of slow-roll inflation. The method relies on the determination of an effective…

Cosmology and Nongalactic Astrophysics · Physics 2014-06-03 Christophe Ringeval

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

We derive a closed-form, analytical expression for the spectrum of long-wavelength density perturbations in inflationary models with two (or more) inflaton degrees of freedom that is valid in the slow-roll approximation. We illustrate…

Astrophysics · Physics 2009-09-15 V. F. Mukhanov , Paul J. Steinhardt

Recently we studied inflation models in which the inflaton potential is characterized by an underlying approximate global symmetry. In the first work we pointed out that in such a model curvature perturbations are generated after the end of…

Astrophysics · Physics 2008-11-26 Edward W. Kolb , Antonio Riotto , Alberto Vallinotto

We discuss the latest constraints on a Taylor-expanded scalar inflaton potential, obtained focusing on its observable part only. This is in contrast with other works in which an extrapolation of the potential is applied using the slow-roll…

Astrophysics · Physics 2009-06-23 Wessel Valkenburg

In this paper we use two methods to constrain the the canonical single-field slow-roll inflation model. The first method exploits the analytic slow-roll-parameter dependence of primordial perturbations, and the second consists of a…

Cosmology and Nongalactic Astrophysics · Physics 2025-11-17 Jun Li , Guang-Hai Guo

The inflaton might be coupled to a gauge field through a term f^2(\phi) F_\mu\nu F^\mu\nu. If f \propto a^{-2} where a(t) is the scale factor, the perturbation \delta W of the gauge field generates a potentially observable statistically…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-15 David H. Lyth , Mindaugas Karčiauskas

Starting from parametrization of scalar perturbations generated during inflation in terms of $e$--fold $N$ and using an approach recently developed by Starobinsky, dubbed "direct smooth reconstruction", we show that, in the slow--roll…

General Relativity and Quantum Cosmology · Physics 2024-01-26 Gianluca Giacomozzi , Sergio Zerbini

The ultra-slow-roll (USR) inflationary models predict large-amplitude scalar perturbations at small scales which can lead to the primordial black hole production and scalar-induced gravitational waves. In general scalar perturbations in the…

Cosmology and Nongalactic Astrophysics · Physics 2020-04-29 Jing Liu , Zong-Kuan Guo , Rong-Gen Cai

Inflation is often described through the dynamics of a scalar field, slow-rolling in a suitable potential. Ultimately, this inflaton must be identified as the expectation value of a quantum field, evolving in a quantum effective potential.…

High Energy Physics - Phenomenology · Physics 2021-05-11 Jens O. Andersen , Magdalena Eriksson , Anders Tranberg

We use cosmic microwave background (CMB) data from the 9-year WMAP release to derive constraints on monodromy inflation, which is characterized by a linear inflaton potential with a periodic modulation. We identify two possible periodic…

Cosmology and Nongalactic Astrophysics · Physics 2013-10-01 Hiranya Peiris , Richard Easther , Raphael Flauger

We place functional constraints on the shape of the inflaton potential from the cosmic microwave background through a variant of the generalized slow roll approximation that allows large amplitude, rapidly changing deviations from…

Cosmology and Nongalactic Astrophysics · Physics 2010-09-01 Cora Dvorkin , Wayne Hu

We study models of inflation where the inflaton corresponds to a flat direction in field space and its mass term is generated by gravity mediated soft supersymmetry breaking at high scale. Assuming the inflaton to have non negligible…

High Energy Physics - Phenomenology · Physics 2007-05-23 Laura Covi

In this paper we operate under the assumption that no tensors from inflation will be measured in the future by the dedicated experiments and argue that, while for single-field slow-roll models of inflation the running of the spectral index…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-03 Matteo Biagetti , Alex Kehagias , Antonio Riotto

We study a radion model for inflation and density perturbation identifying the scalar field arising from the five-dimensional gravity on $M_4 x S^1$ with the inflaton. The inflaton potential arising from 5D graviton and matter one-loop…

High Energy Physics - Theory · Physics 2016-06-21 Yuichi Fukazawa , Takeo Inami , Yoji Koyama

We develop a fast technique based on the generalized slow roll (GSR) approach for computing the curvature bispectrum of inflationary models with features. We show that all triangle configurations can be expressed in terms of three simple…

Cosmology and Nongalactic Astrophysics · Physics 2012-03-02 Peter Adshead , Wayne Hu , Cora Dvorkin , Hiranya V. Peiris

We study slow-roll inflation as a common feature in Metric-affine Theories of Gravity. In particular, we take into account extended metric, teleparallel and symmetric-teleparallel theories of gravity, based on different geometric…

General Relativity and Quantum Cosmology · Physics 2024-09-02 Salvatore Capozziello , Mehdi Shokri

We explore the noncommutative effect on single field inflation and compare with WMAP five-year data. First, we calculate the noncommutative effect from the potential and dynamical terms, and construct the general form of modified power…

Astrophysics · Physics 2009-06-18 Hong-Guang Zhang , Jie Ren , Xin-He Meng

We investigate the constant-roll inflation with non-minimally kinetic coupling to the Einstein tensor. With the slow-roll parameter $\eta_\phi = -\ddot{\phi}/(H\dot{\phi})$ being a constant, we calculate the power spectra for scalar and…

General Relativity and Quantum Cosmology · Physics 2024-07-22 Jie Liu , Yungui Gong , Zhu Yi

After giving a pedagogical review we clarify that the stochastic approach to inflation is generically reliable only at zeroth order in the (geometrical) slow-roll parameter $\epsilon_1$ if and only if $\epsilon_2^2\ll 6/\epsilon_1$, with…

General Relativity and Quantum Cosmology · Physics 2019-04-10 Diego Cruces , Cristiano Germani , Tomislav Prokopec