scholarly journals Generating scale-invariant tensor perturbations in the non-inflationary universe

2014 ◽  
Vol 736 ◽  
pp. 488-493 ◽  
Author(s):  
Mingzhe Li
Keyword(s):  
Inflationary Universe ◽  
Scale Invariant ◽  
Invariant Tensor ◽  
Tensor Perturbations

scholarly journals Scale-invariant tensor spectrum from conformal gravity

2015 ◽  
Vol 30 (32) ◽  
pp. 1550172 ◽  
Author(s):  
Yun Soo Myung ◽  
Taeyoon Moon
Keyword(s):  
Power Spectrum ◽  
Mass Parameter ◽  
Conformal Gravity ◽  
De Sitter ◽  
Scale Invariant ◽  
Tensor Power ◽  
Invariant Tensor ◽  
Tensor Perturbations

We study cosmological tensor perturbations generated during de Sitter inflation in the conformal gravity with mass parameter [Formula: see text]. It turns out that tensor power spectrum is scale-invariant.

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 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 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.

Scale-invariant effective action with torsion

1992 ◽  
Vol 70 (4) ◽  
pp. 238-241 ◽  
Author(s):  
W. F. Kao
Keyword(s):  
Exact Solution ◽  
Cosmological Constant ◽  
Early Universe ◽  
Effective Action ◽  
Effective Theory ◽  
Inflationary Universe ◽  
Scale Invariant ◽  
Torsion Field ◽  
Friedmann Robertson Walker

We considered a four-dimensional scale-invariant effective theory with a torsion field conformally coupled to a metric field. We find that the contribution from the torsion field is negligible in the evolution of the early universe. An exact solution is also obtained for k = 0 Friedmann–Robertson–Walker space in the vanishing cosmological constant limit. This solution is also a good approximation to k ≠ 0 spaces. Possible implications to the inflationary universe are also discussed.

Some topics on scale-invariant perturbations from noninflationary universe

2017 ◽  
Vol 26 (01) ◽  
pp. 1740005 ◽  
Author(s):  
Mingzhe Li
Keyword(s):  
Early Universe ◽  
Main Property ◽  
Scalar Fields ◽  
Scalar Perturbation ◽  
Scale Invariant ◽  
Production Scale ◽  
Tensor Perturbation ◽  
Invariant Tensor ◽  
Cyclic Universe ◽  
Universe Models

In this paper, we review some topics on generations of scale-invariant primordial scalar and tensor perturbations in the early universe models different from inflation. The content includes generation of scale-invariant and Gaussian scalar perturbation in the ekpyrotic/cyclic universe, and production scale-invariant tensor perturbation in contracting universe. The main property of the models reviewed in this paper is the nonminimal couplings, include nonminimal couplings between the scalar fields and those to the gravity. By introducing these couplings, it is not difficult to achieve scale-invariances for the perturbations in the early universe models alternative to inflation.

Sign in / Sign up

Export Citation Format

Share Document