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Seemingly unrelated models of inflation that originate from different physical setups yield, in some cases, identical predictions for the currently constrained inflationary observables. In order to classify the available models, we propose…

High Energy Physics - Phenomenology · Physics 2017-04-19 Laur Järv , Kristjan Kannike , Luca Marzola , Antonio Racioppi , Martti Raidal , Mihkel Rünkla , Margus Saal , Hardi Veermäe

Isocurvature perturbations naturally occur in models of inflation consisting of more than one scalar field. In this paper we calculate the spectrum of isocurvature perturbations generated at the end of inflation for three different…

Cosmology and Nongalactic Astrophysics · Physics 2012-03-09 Ian Huston , Adam J. Christopherson

It has become standard practice to take the logarithmic growth of the scale factor as a measure of the amount of inflation, despite the well-known fact that this is only an approximation for the true amount of inflation required to solve…

Cosmology and Nongalactic Astrophysics · Physics 2016-09-02 Sirichai Chongchitnan

Precise understanding of nonlinear evolution of cosmological perturbations during inflation is necessary for the correct interpretation of measurements of non-Gaussian correlations in the cosmic microwave background and the large-scale…

General Relativity and Quantum Cosmology · Physics 2013-05-30 Naonori S. Sugiyama , Eiichiro Komatsu , Toshifumi Futamase

We present the first computation of the cosmological perturbations generated during inflation up to second order in deviations from the homogeneous background solution. Our results, which fully account for the inflaton self-interactions as…

Astrophysics · Physics 2010-04-05 V. Acquaviva , N. Bartolo , S. Matarrese , A. Riotto

During inflation explicit perturbative computations of quantum field theories which contain massless, non-conformal fields exhibit secular effects that grow as powers of the logarithm of the inflationary scale factor. Starobinskii's…

General Relativity and Quantum Cosmology · Physics 2009-11-11 N. C. Tsamis , R. P. Woodard

We present a simple way to calculate non-Gaussianity in inflation using fully non-linear equations on long wavelengths with stochastic sources to take into account the short-wavelength quantum fluctuations. Our formalism includes both…

Astrophysics · Physics 2009-11-10 G. I. Rigopoulos , E. P. S. Shellard , B. J. W. van Tent

The formalism of stochastic inflation is a powerful tool for analyzing the backreaction of cosmological perturbations, and making precise predictions for inflationary observables. We demonstrate this with the simple $m^2\phi^2$ model of…

High Energy Physics - Theory · Physics 2015-09-02 Laurence Perreault Levasseur , Evan McDonough

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

During inflation explicit perturbative computations of quantum field theories which contain massless, non-conformal fields exhibit secular effects that grow as powers of the logarithm of the inflationary scale factor. Starobinski\u{\i}'s…

Astrophysics · Physics 2009-11-10 R. P. Woodard

For simple inflationary models, we provide a consistent and complete scheme by which the macro-physical details of early universe inflation may be determined explicitly from the underlying micro-physical theory. We examine inflationary…

High Energy Physics - Phenomenology · Physics 2007-05-23 D. Cormier

A recent variant of the inflationary paradigm is that the ``primordial'' curvature perturbations come from quantum fluctuations of a scalar field, subdominant and effectively massless during inflation, called the ``curvaton'', instead of…

Astrophysics · Physics 2009-11-10 David Langlois , Filippo Vernizzi

In this paper we develop the formalism for the stochastic approach to inflation at all order in slow-roll parameters. This is done by including the momentum and Hamiltonian constraints into the stochastic equations. We then specialise to…

General Relativity and Quantum Cosmology · Physics 2022-02-09 Diego Cruces , Cristiano Germani

We extend the formalism to calculate non-Gaussianity of primordial curvature perturbations produced by preheating in the presence of a light scalar field. The calculation is carried out in the separate universe approximation using the…

Cosmology and Nongalactic Astrophysics · Physics 2024-05-31 Pulkit S. Ghoderao , Arttu Rajantie

Stochastic inflation resolves primordial perturbations non-linearly, probing their probability distribution deep into its non-Gaussian tail. The strongest perturbations collapse into primordial black holes. In typical black-hole-producing…

Cosmology and Nongalactic Astrophysics · Physics 2023-08-07 Eemeli Tomberg

The spectrum of primordial fluctuations from inflation can be obtained using a mathematically controlled, and systematically extendable, uniform approximation. Closed-form expressions for power spectra and spectral indices may be found…

How much does the curvature perturbation change after it leaves the horizon, and when should one evaluate the power spectrum? To answer these questions we study single field inflation models numerically, and compare the evolution of…

Cosmology and Nongalactic Astrophysics · Physics 2013-02-26 Ellie Nalson , Adam J. Christopherson , Ian Huston , Karim A. Malik

We compute the growth of the mean square of quantum fluctuations of test fields with small effective mass during a slowly changing, nearly de Sitter stage which took place in different inflationary models. We consider a minimally coupled…

High Energy Physics - Theory · Physics 2010-10-11 F. Finelli , G. Marozzi , A. A. Starobinsky , G. P. Vacca , G. Venturi

We compute the primordial scalar, vector and tensor metric perturbations arising from quantum field inflation. Quantum field inflation takes into account the nonperturbative quantum dynamics of the inflaton consistently coupled to the…

Astrophysics · Physics 2009-11-11 F. J. Cao

We compute one-loop corrections to the power spectrum of the curvature perturbation in single-field slow-roll inflation arising from gravitons and inflaton interactions. The quantum corrections due to gravitons to the power spectrum of the…

Astrophysics · Physics 2011-07-13 Emanuela Dimastrogiovanni , Nicola Bartolo