scholarly journals Dynamically generated inflation from non-Riemannian volume forms

2019 ◽  
Vol 79 (9) ◽  
Author(s):  
D. Benisty ◽  
E. I. Guendelman ◽  
E. Nissimov ◽  
S. Pacheva
Keyword(s):  
Scalar Field ◽  
Dynamical Systems ◽  
Modified Gravity ◽  
Point Of View ◽  
Riemannian Volume ◽  
Riemannian Spacetime ◽  
Cosmological Solutions ◽  
Volume Forms ◽  
Matter Fields ◽  
Type Potential

Abstract We propose a simple modified gravity model without any initial matter fields in terms of several alternative non-Riemannian spacetime volume elements within the metric (second order) formalism. We show how the non-Riemannian volume-elements, when passing to the physical Einstein frame, create a canonical scalar field and produce dynamically a non-trivial inflationary-type potential for the latter with a large flat region and a stable low-lying minimum. We study the evolution of the cosmological solutions from the point of view of theory of dynamical systems. The theory predicts the spectral index $$n_s \approx 0.96$$ns≈0.96 and the tensor-to-scalar ratio $$r \approx 0.002$$r≈0.002 for 60 e-folds, which is in accordance with the observational data. In the future Euclid and SPHEREx missions or the BICEP3 experiment are expected to provide experimental evidence to test those predictions.

scholarly journals Dynamically Generated Inflationary ΛCDM

Symmetry ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 481 ◽  
Author(s):  
David Benisty ◽  
Eduardo I. Guendelman ◽  
Emil Nissimov ◽  
Svetlana Pacheva
Keyword(s):  
Dark Matter ◽  
Scalar Field ◽  
Momentum Tensor ◽  
Primary Objective ◽  
Volume Element ◽  
Einstein Frame ◽  
Riemannian Volume ◽  
Power Spectral ◽  
Riemannian Spacetime ◽  
Lagrangian Action

Our primary objective is to construct a plausible, unified model of inflation, dark energy and dark matter from a fundamental Lagrangian action first principle, wherein all fundamental ingredients are systematically dynamically generated starting from a very simple model of modified gravity interacting with a single scalar field employing the formalism of non-Riemannian spacetime volume-elements. The non-Riemannian volume element in the initial scalar field action leads to a hidden, nonlinear Noether symmetry which produces an energy-momentum tensor identified as the sum of a dynamically generated cosmological constant and dust-like dark matter. The non-Riemannian volume-element in the initial Einstein–Hilbert action upon passage to the physical Einstein-frame creates, dynamically, a second scalar field with a non-trivial inflationary potential and with an additional interaction with the dynamically generated dark matter. The resulting Einstein-frame action describes a fully dynamically generated inflationary model coupled to dark matter. Numerical results for observables such as the scalar power spectral index and the tensor-to-scalar ratio conform to the latest 2018 PLANCK data.

scholarly journals Dynamically Generated Inflationary Lambda-CDM

2020 ◽  
Author(s):  
David Benisty ◽  
Eduardo I. Guendelman ◽  
Emil Nissimov ◽  
Svetlana Pacheva
Keyword(s):  
Dark Matter ◽  
Scalar Field ◽  
Momentum Tensor ◽  
Primary Objective ◽  
Volume Element ◽  
Einstein Frame ◽  
Riemannian Volume ◽  
Power Spectral ◽  
Riemannian Spacetime ◽  
Lagrangian Action

Our primary objective is to construct a plausible unified model of inflation, dark energy and dark matter from a fundamental Lagrangian action first principle, where all fundamental ingredients are systematically dynamically generated starting from a very simple model of modified gravity interacting with a single scalar field employing the formalism of non-Riemannian spacetime volume-elements. The non-Riemannian volume element in the initial scalar field action leads to a hidden nonlinear Noether symmetry which produces energy-momentum tensor identified as a sum of a dynamically generated cosmological constant and a dust-like dark matter. The non-Riemannian volume-element in the initial Einstein-Hilbert action upon passage to the physical Einstein-frame creates dynamically a second scalar field with a non-trivial inflationary potential and with an additional interaction with the dynamically generated dark matter. The resulting Einstein-frame action describes a fully dynamically generated inflationary model coupled to dark matter. Numerical results for observables such as the scalar power spectral index and the tensor-to-scalar ratio conform to the latest 2018 PLANCK data.

scholarly journals STABLE SUPER-INFLATING COSMOLOGICAL SOLUTIONS IN f(R)-GRAVITY

2012 ◽  
Vol 21 (06) ◽  
pp. 1250051 ◽  
Author(s):  
MIKHAIL M. IVANOV ◽  
ALEXEY V. TOPORENSKY
Keyword(s):  
Scalar Field ◽  
Modified Gravity ◽  
Field Potential ◽  
Cosmological Solutions ◽  
R Functions

We consider super-inflating solutions in modified gravity for several popular families of f(R) functions. Using scalar field reformulation of f(R)-gravity we describe how the form of effective scalar field potential can be used for explaining existence of stable super-inflation solutions in the theory under consideration. Several new solutions of this type have been found analytically and checked numerically.

scholarly journals On some kinds of dense orbits in general nonautonomous dynamical systems

2020 ◽  
Vol 7 (1) ◽  
pp. 163-175
Author(s):  
Mehdi Pourbarat
Keyword(s):  
Dynamical Systems ◽  
Initial Conditions ◽  
Point Of View ◽  
Topological Conjugacy ◽  
Topological Transitivity ◽  
Nonautonomous Systems ◽  
Nonautonomous Dynamical Systems ◽  
Sensitive Dependence ◽  
Dense Orbits

AbstractWe study the theory of universality for the nonautonomous dynamical systems from topological point of view related to hypercyclicity. The conditions are provided in a way that Birkhoff transitivity theorem can be extended. In the context of generalized linear nonautonomous systems, we show that either one of the topological transitivity or hypercyclicity give sensitive dependence on initial conditions. Meanwhile, some examples are presented for topological transitivity, hypercyclicity and topological conjugacy.

scholarly journals Noninertial effects on a scalar field in a spacetime with a magnetic screw dislocation

2019 ◽  
Vol 79 (10) ◽  
Author(s):  
Ricardo L. L. Vitória
Keyword(s):  
Scalar Field ◽  
Screw Dislocation ◽  
Bound States ◽  
Charged Scalar ◽  
Wall Potential ◽  
Noninertial Effects ◽  
Klein Gordon ◽  
Coulomb Type ◽  
Charged Scalar Field ◽  
Type Potential

Abstract We investigate rotating effects on a charged scalar field immersed in spacetime with a magnetic screw dislocation. In addition to the hard-wall potential, which we impose to satisfy a boundary condition from the rotating effect, we insert a Coulomb-type potential and the Klein–Gordon oscillator into this system, where, analytically, we obtain solutions of bound states which are influenced not only by the spacetime topology, but also by the rotating effects, as a Sagnac-type effect modified by the presence of the magnetic screw dislocation.

SURVEY Towards a global view of dynamical systems, for the C1-topology

2011 ◽  
Vol 31 (4) ◽  
pp. 959-993 ◽  
Author(s):  
C. BONATTI
Keyword(s):  
Dynamical Systems ◽  
Compact Manifold ◽  
Global Structure ◽  
Point Of View ◽  
List Type ◽  
Global View ◽  
Local Phenomenon ◽  
Generic Dynamics

AbstractThis paper suggests a program for getting a global view of the dynamics of diffeomorphisms, from the point of view of the C1-topology. More precisely, given any compact manifold M, one splits Diff1(M) into disjoint C1-open regions whose union is C1-dense, and conjectures state that each of these open sets and their complements is characterized by the presence of: •either a robust local phenomenon;•or a global structure forbidding this local phenomenon. Other conjectures state that some of these regions are empty. This set of conjectures draws a global view of the dynamics, putting in evidence the coherence of the numerous recent results on C1-generic dynamics.

LOCALIZATION OF MATTERS ON A NON-Z2-SYMMETRIC THICK BRANE

2010 ◽  
Vol 25 (07) ◽  
pp. 511-523
Author(s):  
JUN LIANG ◽  
YI-SHI DUAN
Keyword(s):  
Vector Field ◽  
Scalar Field ◽  
Yukawa Coupling ◽  
Spinor Field ◽  
Zero Mode ◽  
Parallel Transport ◽  
Type Coupling ◽  
Matter Fields

We study localization of various matter fields on a non-Z2-symmetric scalar thick brane in a pure geometric Weyl integrable manifold in which variations in the length of vectors during parallel transport are allowed and a geometric scalar field is involved in its formulation. It is shown that, for spin 0 scalar field, the massless zero mode can be normalized on the brane. Spin 1 vector field cannot be normalized on the brane. And there is no spinor field which can be trapped on the brane for the case of no Yukawa-type coupling. By introducing the appropriate Yukawa coupling, the left or right chiral fermionic zero mode can be localized on the brane.

scholarly journals Polarized Initial States of Primordial Gravitational Waves

Symmetry ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 672
Author(s):  
Sugumi Kanno ◽  
Jiro Soda
Keyword(s):  
Gravitational Waves ◽  
Modified Gravity ◽  
Coherent States ◽  
Inflationary Universe ◽  
Dynamical Generation ◽  
Primordial Gravitational Waves ◽  
Initial States ◽  
Matter Fields

Polarizations of primordial gravitational waves can be relevant when considering an inflationary universe in modified gravity or when matter fields survive during inflation. Such polarizations have been discussed in the Bunch–Davies vacuum. Instead of taking into account the dynamical generation of polarizations of gravitational waves, in this paper, we consider polarized initial states constructed from S U ( 2 ) coherent states. We then evaluate the power spectrums of the primordial gravitational waves in the states.

scholarly journals Tachyonic matter cosmology with exponential and hyperbolic potentials

2017 ◽  
Vol 26 (02) ◽  
pp. 1750012 ◽  
Author(s):  
B. Pourhassan ◽  
J. Naji
Keyword(s):  
Scalar Field ◽  
Observational Data ◽  
Cosmological Parameters ◽  
Field Potentials ◽  
Exponential Potential ◽  
Frw Universe ◽  
Hyperbolic Cosine ◽  
Special Cases ◽  
Friedmann Robertson Walker ◽  
Type Potential

In this paper, we consider tachyonic matter in spatially flat Friedmann–Robertson–Walker (FRW) universe, and obtain behavior of some important cosmological parameters for two special cases of potentials. First, we assume the exponential potential and then consider hyperbolic cosine type potential. In both cases, we obtain behavior of the Hubble, deceleration and EoS parameters. Comparison with observational data suggest the model with hyperbolic cosine type scalar field potentials has good model to describe universe.

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