scholarly journals Lattice simulations of inflation

2021 ◽  
Vol 2021 (12) ◽  
pp. 010
Author(s):  
Angelo Caravano ◽  
Eiichiro Komatsu ◽  
Kaloian D. Lozanov ◽  
Jochen Weller
Keyword(s):  
Scalar Field ◽  
Power Spectrum ◽  
Linear Perturbation ◽  
Inflationary Universe ◽  
Lattice Simulation ◽  
Scale Invariant ◽  
Step Potential ◽  
Lattice Codes ◽  
Linear Perturbation Theory ◽  
Single Field

Abstract The scalar field theory of cosmological inflation constitutes nowadays one of the preferred scenarios for the physics of the early universe. In this paper we aim at studying the inflationary universe making use of a numerical lattice simulation. Various lattice codes have been written in the last decades and have been extensively used for understating the reheating phase of the universe, but they have never been used to study the inflationary phase itself far from the end of inflation (i.e. about 50 e-folds before the end of inflation). In this paper we use a lattice simulation to reproduce the well-known results of some simple models of single-field inflation, particularly for the scalar field perturbation. The main model that we consider is the standard slow-roll inflation with an harmonic potential for the inflaton field. We explore the technical aspects that need to be accounted for in order to reproduce with precision the nearly scale invariant power spectrum of inflaton perturbations. We also consider the case of a step potential, and show that the simulation is able to correctly reproduce the oscillatory features in the power spectrum of this model. Even if a lattice simulation is not needed in these cases, that are well within the regime of validity of linear perturbation theory, this sets the basis to future work on using lattice simulations to study more complicated models of inflation.

scholarly journals NEW HOLOGRAPHIC CHAPLYGIN GAS MODEL OF DARK ENERGY

2011 ◽  
Vol 20 (03) ◽  
pp. 281-297 ◽  
Author(s):  
M. MALEKJANI ◽  
A. KHODAM-MOHAMMADI
Keyword(s):  
Dark Energy ◽  
Scalar Field ◽  
Chaplygin Gas ◽  
Accelerated Expansion ◽  
Linear Perturbation ◽  
Generalized Chaplygin Gas ◽  
Infrared Cutoff ◽  
Scalar Field Models ◽  
Linear Perturbation Theory ◽  
Limiting Case

In this work, we investigate the holographic dark energy model with a new infrared cutoff (new HDE model), proposed by Granda and Oliveros. Using this new definition for the infrared cutoff, we establish the correspondence between the new HDE model and the standard Chaplygin gas (SCG), generalized Chaplygin gas (GCG) and modified Chaplygin gas (MCG) scalar field models in a nonflat universe. The potential and dynamics for these scalar field models, which describe the accelerated expansion of the universe, are reconstructed. According to the evolutionary behavior of the new HDE model, we derive the same form of dynamics and potential for the different SCG, GCG and MCG models. We also calculate the squared sound speed of the new HDE model as well as the SCG, GCG and MCG models, and investigate the new HDE Chaplygin gas models from the viewpoint of linear perturbation theory. In addition, all results in the nonflat universe are discussed in the limiting case of the flat universe, i.e. k = 0.

scholarly journals SCALAR DEFORMATIONS OF SCHWARZSCHILD HOLES AND THEIR STABILITY

1998 ◽  
Vol 13 (05) ◽  
pp. 741-764 ◽  
Author(s):  
HELGE DENNHARDT ◽  
OLAF LECHTENFELD
Keyword(s):  
Scalar Field ◽  
Energy Condition ◽  
Linear Perturbation ◽  
Dominant Energy Condition ◽  
Stability Criteria ◽  
Field Equations ◽  
Effective Potentials ◽  
Scalar Hair ◽  
Linear Perturbation Theory ◽  
Scalar Field Equations

We construct two solutions of the minimally coupled Einstein-scalar field equations, representing regular deformations of Schwarzschild black holes by a self-interacting, static, scalar field. One solution features an exponentially decaying scalar field and a triple-well interaction potential; the other one is completely analytic and sprouts Coulomb-like scalar hair. Both evade the no-hair theorem by having partially negative potential, in conflict with the dominant energy condition. The linear perturbation theory around such backgrounds is developed in general, and yields stability criteria in terms of effective potentials for an analog Schrödinger problem. We can test for more than half of the perturbation modes, and our solutions prove to be stable against those.

scholarly journals Quintessential Inflation with Dynamical Higgs Generation as an Affine Gravity

2020 ◽  
Author(s):  
David Benisty ◽  
Eduardo Guendelman ◽  
Emil Nissimov ◽  
Svetlana Pacheva
Keyword(s):  
Scalar Field ◽  
Modified Gravity ◽  
Riemannian Metric ◽  
Explicit Representation ◽  
Inflationary Universe ◽  
Inflationary Model ◽  
Scale Invariant ◽  
Inflationary Scenario ◽  
Higgs Effect ◽  
Affine Gravity

First, we propose a scale-invariant modified gravity interacting with a neutral scalar inflaton and a Higgs-like SU(2)xU(1) iso-doublet scalar field based on the formalism of non-Riemannian (metric-independent) spacetime volume-elements. This model describes in the physical Einstein frame a quintessential inflationary scenario driven by the "inflaton" together with gravity-inflaton assisted dynamical spontaneous SU(2)xU(1) symmetry breaking in the post-inflationary universe, whereas SU(2)xU(1) symmetry remains intact in the inflationary epoch. Next, we find the explicit representation of the latter quintessential inflationary model with a dynamical Higgs effect as an Eddington-type purely affine gravity.

scholarly journals Quintessential Inflation with Dynamical Higgs Generation as an Affine Gravity

Symmetry ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 734 ◽  
Author(s):  
David Benisty ◽  
Eduardo I. Guendelman ◽  
Emil Nissimov ◽  
Svetlana Pacheva
Keyword(s):  
Scalar Field ◽  
Symmetry Breaking ◽  
Modified Gravity ◽  
Riemannian Metric ◽  
Explicit Representation ◽  
Inflationary Universe ◽  
Inflationary Model ◽  
Scale Invariant ◽  
Higgs Effect ◽  
Affine Gravity

First, we propose a scale-invariant modified gravity interacting with a neutral scalar inflaton and a Higgs-like S U ( 2 ) × U ( 1 ) iso-doublet scalar field based on the formalism of non-Riemannian (metric-independent) spacetime volume-elements. This model describes, in the physical Einstein frame, a quintessential inflationary scenario driven by the “inflaton” together with the gravity-“inflaton” assisted dynamical spontaneous S U ( 2 ) × U ( 1 ) symmetry breaking in the post-inflationary universe, whereas the S U ( 2 ) × U ( 1 ) symmetry remains intact in the inflationary epoch. Next, we find the explicit representation of the latter quintessential inflationary model with a dynamical Higgs effect as an Eddington-type purely affine gravity.

scholarly journals Quintessential Inflation with Dynamical Higgs Generation as an Affine Gravity

2020 ◽  
Author(s):  
David Benisty ◽  
Eduardo Guendelman ◽  
Emil Nissimov ◽  
Svetlana Pacheva
Keyword(s):  
Scalar Field ◽  
Symmetry Breaking ◽  
Modified Gravity ◽  
Riemannian Metric ◽  
Explicit Representation ◽  
Inflationary Universe ◽  
Inflationary Model ◽  
Scale Invariant ◽  
Higgs Effect ◽  
Affine Gravity

First, we propose a scale-invariant modified gravity interacting with a neutral scalar inflaton and a Higgs-like SU(2) × U(1) iso-doublet scalar field based on the formalism of non-Riemannian (metric-independent) spacetime volume-elements. This model describes in the physical Einstein frame a quintessential inflationary scenario driven by the “inflaton” together with gravity-inflaton assisted dynamical spontaneous SU(2) × U(1) symmetry breaking in the post-inflationary universe, whereas SU(2) × U(1) symmetry remains intact in the inflationary epoch. Next, we find the explicit representation of the latter quintessential inflationary model with a dynamical Higgs effect as an Eddington-type purely affine gravity.

Dynamics of single-field inflation in the framework of holographic f(T) gravity

2018 ◽  
Vol 15 (10) ◽  
pp. 1850167 ◽  
Author(s):  
Surajit Chattopadhyay ◽  
Antonio Pasqua ◽  
Irina Radinschi ◽  
Aroonkumar Beesham
Keyword(s):  
Dark Energy ◽  
Scalar Field ◽  
Energy Density ◽  
Linear Form ◽  
Index Formula ◽  
Inflationary Universe ◽  
Ricci Dark Energy ◽  
Slow Roll ◽  
Scalar Spectral Index ◽  
Single Field

In the work reported in the present paper, we have considered the inflationary dynamics inspired by holographic Ricci dark energy (HRDE) with the energy density [Formula: see text] in the framework of [Formula: see text] gravity. We have considered a [Formula: see text]-gravity model in linear form, which is sourced by a canonical scalar field due to the HRDE. We have investigated an inflationary Universe in this framework through slow-roll formalism. We also studied the scalar spectral index [Formula: see text] and tensor-to-scalar ratio [Formula: see text], which have come out to be in agreement with WMAP[Formula: see text]BAO[Formula: see text][Formula: see text] and Planck 2015 data.

scholarly journals EFFECTS OF BLACK HOLES ON INFLATON PERTURBATION

2012 ◽  
Vol 12 ◽  
pp. 272-279
Author(s):  
HING-TONG CHO ◽  
KIN-WANG NG ◽  
I-CHIN WANG
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Scalar Field ◽  
Power Spectrum ◽  
Perturbation Approach ◽  
Inflationary Universe ◽  
Cosmological Horizon ◽  
De Sitter ◽  
Small Black Hole ◽  
Free Scalar

We calculate quantum fluctuations of a free scalar field in the Schwarzschild-de Sitter space-time, adopting the planar coordinates that is pertinent to the presence of a black hole in an inflationary universe. In a perturbation approach, doing expansion in powers of a small black hole event horizon compared to the de Sitter cosmological horizon, we obtain the scalar power spectrum.

scholarly journals Abundance of Primordial Black Holes in Peak Theory for an Arbitrary Power Spectrum

2020 ◽  
Author(s):  
Chul-Moon Yoo ◽  
Tomohiro Harada ◽  
Shin’ichi Hirano ◽  
Kazunori Kohri
Keyword(s):  
Mass Spectrum ◽  
Power Spectrum ◽  
Environmental Effect ◽  
Window Function ◽  
Radial Coordinate ◽  
Primordial Black Holes ◽  
Scale Invariant ◽  
Curvature Perturbation ◽  
Arbitrary Power ◽  
Nonlinear Relation

Abstract We modify the procedure to estimate PBH abundance proposed in Ref. [1] so that it can be applied to a broad power spectrum such as the scale-invariant flat power spectrum. In the new procedure, we focus on peaks of the Laplacian of the curvature perturbation △ ζ and use the values of △ ζ and △ △ ζ at each peak to specify the profile of ζ as a function of the radial coordinate while the values of ζ and △ ζ are used in Ref. [1]. The new procedure decouples the larger-scale environmental effect from the estimate of PBH abundance. Because the redundant variance due to the environmental effect is eliminated, we obtain a narrower shape of the mass spectrum compared to the previous procedure in Ref. [1]. Furthermore, the new procedure allows us to estimate PBH abundance for the scale-invariant flat power spectrum by introducing a window function. Although the final result depends on the choice of the window function, we show that the k-space tophat window minimizes the extra reduction of the mass spectrum due to the window function. That is, the k-space tophat window has the minimum required property in the theoretical PBH estimation. Our procedure makes it possible to calculate the PBH mass spectrum for an arbitrary power spectrum by using a plausible PBH formation criterion with the nonlinear relation taken into account.

Sign in / Sign up

Export Citation Format

Share Document