scholarly journals Noether symmetry approach in f (T, B) teleparallel gravity with a fermionic field

2021 ◽  
Vol 2090 (1) ◽  
pp. 012058
Author(s):  
Yerlan Myrzakulov ◽  
Sabit Bekov ◽  
Kairat Myrzakulov
Keyword(s):  
Cosmological Model ◽  
Teleparallel Gravity ◽  
Noether Symmetry ◽  
Accelerated Expansion ◽  
Late Time ◽  
Fermionic Field ◽  
Symmetry Approach ◽  
Expansion Of The Universe ◽  
Isotropic Cosmological Model ◽  
The Universe

Abstract In this work, we consider a homogeneous and isotropic cosmological model of the universe in f (T, B) gravity with non-minimally coupled fermionic field. In order to find the form of the coupling function F(Ψ), the potential function V (Ψ) of the fermionic field and the function f (T, B), we found through the Noether symmetry approach. The results obtain are coincide with the observational data that describe the late-time accelerated expansion of the universe.

scholarly journals A novel teleparallel dark energy model

2016 ◽  
Vol 25 (02) ◽  
pp. 1650025 ◽  
Author(s):  
Giovanni Otalora
Keyword(s):  
Dark Energy ◽  
Scalar Field ◽  
Teleparallel Gravity ◽  
Accelerated Expansion ◽  
Late Time ◽  
De Sitter ◽  
Sitter Group ◽  
Current State ◽  
Expansion Of The Universe ◽  
The Universe

Although equivalent to general relativity, teleparallel gravity (TG) is conceptually speaking a completely different theory. In this theory, the gravitational field is described by torsion, not by curvature. By working in this context, a new model is proposed in which the four-derivative of a canonical scalar field representing dark energy is nonminimally coupled to the “vector torsion”. This type of coupling is motivated by the fact that a scalar field couples to torsion through its four-derivative, which is consistent with local spacetime kinematics regulated by the de Sitter group [Formula: see text]. It is found that the current state of accelerated expansion of the universe corresponds to a late-time attractor that can be (i) a dark energy-dominated de Sitter solution ([Formula: see text]), (ii) a quintessence-type solution with [Formula: see text], or (iii) a phantom-type [Formula: see text] dark energy.

scholarly journals Dirac Field as a Source of the Inflation in2+1Dimensional Teleparallel Gravity

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Ganim Gecim ◽  
Yusuf Sucu
Keyword(s):  
Early Time ◽  
Teleparallel Gravity ◽  
Noether Symmetry ◽  
Dirac Field ◽  
Late Time ◽  
Late Time Acceleration ◽  
Symmetry Approach ◽  
Gauge Term ◽  
Acceleration Of The Universe ◽  
The Universe

In this paper, we study early-time inflation and late-time acceleration of the universe by nonminimally coupling the Dirac field with torsion in the spatially flat Friedman-Robertson-Walker (FRW) cosmological model background. The results obtained by the Noether symmetry approach with and without a gauge term are compared. Additionally, we compare these results with that of the3+1dimensional teleparallel gravity under Noether symmetry approach. And we see that the study explains early-time inflation and late-time acceleration of the universe.

scholarly journals Noether symmetries of Einstein-aether scalar field cosmology

2020 ◽  
Vol 80 (11) ◽  
Author(s):  
Yusuf Kucukakca ◽  
Amin Rezaei Akbarieh
Keyword(s):  
Scalar Field ◽  
Noether Symmetry ◽  
Accelerated Expansion ◽  
Noether Symmetries ◽  
Field Equations ◽  
Symmetry Approach ◽  
Expansion Of The Universe ◽  
Frw Metric ◽  
Scalar Field Cosmology ◽  
The Universe

AbstractIn this paper, we explore an Einstein-aether cosmological model by adding the scalar field in which it has an interaction with the aether field. For the cosmological implications of the model, we consider that the universe can be described by the spatially flat FRW metric together with the matter dominated universe. Applying Noether symmetry approach to the point-like Lagrangian we determine the explicit forms of unknown functions i.e. the potential and coupling function. We solve the analytical cosmological solutions of the field equations admitting the Noether symmetry, basically divided into two parts. Our results show that the obtained solutions lead to an accelerated expansion of the universe. We also discuss the tensor perturbations within the framework of this model in order to get information about the mass of gravitational waves.

scholarly journals Dynamical Stability of Bulk Viscous Isotropic and Homogeneous Universe

Universe ◽  
2019 ◽  
Vol 5 (8) ◽  
pp. 185
Author(s):  
Muhammad Sharif ◽  
Qanitah Ama-Tul-Mughani
Keyword(s):  
Accelerated Expansion ◽  
Stationary Points ◽  
Late Time ◽  
Energy Models ◽  
Bulk Viscous ◽  
Expansion Of The Universe ◽  
Homogeneous Universe ◽  
The Stability ◽  
The Universe ◽  
Autonomous Set

In this paper, we study the phase space portrait of homogeneous and isotropic universe by taking different coupling functions between dark energy models and bulk viscous dark matter. The dimensionless quantities are introduced to establish an autonomous set of equations. To analyze the stability of the cosmos, we evaluate critical points and respective eigenvalues for different dynamical quantities. For bulk viscous matter and radiation in tachyon coupled field, these points show stable evolution when γ ≫ δ but accelerated expansion of the universe for δ > 1 9 . The stability of the universe increases for some stationary points which may correspond to the late-time expansion for the coupled phantom field.

Analysis of observational parameters and stability in extended teleparallel gravity

2020 ◽  
Vol 17 (11) ◽  
pp. 2050158
Author(s):  
A. Y. Shaikh ◽  
B. Mishra
Keyword(s):  
Thermodynamic Temperature ◽  
Teleparallel Gravity ◽  
Entropy Density ◽  
Accelerated Expansion ◽  
Late Time ◽  
General Relativistic ◽  
Basic Equations ◽  
The Stability ◽  
The Universe ◽  
Early Phases

In this paper, we have investigated the stability of General Relativistic Hydrodynamics (GRHD) model in a Friedmann–Robertson–Walker space-time with the volumetric power law in teleparallel gravity. The basic equations are derived along with its thermodynamical aspects. Thermodynamic temperature and entropy density of the model are also obtained. The state finder diagnostic pair and jerk parameter are analyzed to characterize different phases of the universe and the well-known astrophysical phenomena such as look-back time, the luminosity distance with redshift are derived. The model shows an accelerated expansion with inflationary era in the early and the very late time of the cosmic evolution. The GRHD model is stable at the early phases of the universe and is unstable at late times.

scholarly journals Effect of Fast Scale Factor Fluctuations on Cosmological Evolution

Universe ◽  
2021 ◽  
Vol 7 (6) ◽  
pp. 164
Author(s):  
Igor I. Smolyaninov
Keyword(s):  
Quantum Fluctuations ◽  
Scale Factor ◽  
Cosmological Evolution ◽  
Accelerated Expansion ◽  
Late Time ◽  
Cosmological Constant Problem ◽  
Friedmann Equations ◽  
Newtonian Dynamics ◽  
Expansion Of The Universe ◽  
The Universe

In this paper, we study the corrections to the Friedmann equations due to fast fluctuations in the universe scale factor. Such fast quantum fluctuations were recently proposed as a potential solution to the cosmological constant problem. They also induce strong changes to the current sign and magnitude of the average cosmological force, thus making them one of the potential probable causes of the modification of Newtonian dynamics in galaxy-scale systems. It appears that quantum fluctuations in the scale factor also modify the Friedmann equations, leading to a considerable modification of cosmological evolution. In particular, they give rise to the late-time accelerated expansion of the universe, and they may also considerably modify the effective universe potential.

ROLE OF EXTRA DIMENSION IN ACCELERATED EXPANSION

2008 ◽  
Vol 23 (06) ◽  
pp. 909-917 ◽  
Author(s):  
K. D. PUROHIT ◽  
YOGESH BHATT
Keyword(s):  
Cosmological Model ◽  
Extra Dimension ◽  
Accelerated Expansion ◽  
Field Equations ◽  
Four Dimensions ◽  
Scale Factors ◽  
Expansion Of The Universe ◽  
The Universe ◽  
Kaluza Klein

A five-dimensional FRW-type Kaluza–Klein cosmological model is taken to study the role of extra dimension in the expansion of the universe. Relation between scale factors corresponding to conventional four dimensions and the extra dimension has been established. Field equations are solved in order to find out the effect of pressure corresponding to these scale factors. Conditions for accelerated expansion are derived.

scholarly journals A COSMOLOGICAL MODEL WITH FERMIONIC FIELD AND GAUSS–BONNET TERM

2010 ◽  
Vol 25 (06) ◽  
pp. 1267-1278 ◽  
Author(s):  
R. RAKHI ◽  
G. V. VIJAYAGOVINDAN ◽  
K. INDULEKHA ◽  
NOBLE P. ABRAHAM
Keyword(s):  
Cosmological Model ◽  
State Parameter ◽  
The Self ◽  
Late Time ◽  
Fermionic Field ◽  
New Type ◽  
Interaction Term ◽  
The Stability ◽  
The Universe ◽  
Bonnet Term

In this work, a cosmological model inspired by string theory with Gauss–Bonnet term coupled to the fermionic field is taken into consideration. The self-interaction potential is considered as a combination of the scalar and pseudoscalar invariants. Here the cosmological contribution of the coupling of Gauss–Bonnet term with a non-Dirac fermionic field — characterized by an interaction term[Formula: see text] — is investigated. It is observed that the new type of coupling plays a significant role in the accelerating behavior of the universe. Specifically, in addition to the late time acceleration for the universe, [Formula: see text] produces an early decelerating behavior. The behavior of the equation-of-state parameter (w) is such that it guarantees the stability of the theory.

BRANS-DICKE COSMOLOGY WITH FERMIONS AND CHAMELEON MECHANISM

2012 ◽  
Vol 07 ◽  
pp. 174-183
Author(s):  
DAO-JUN LIU ◽  
BIN YANG ◽  
XING-HUA JIN
Keyword(s):  
Scalar Field ◽  
Interaction Potential ◽  
The Self ◽  
Accelerated Expansion ◽  
Late Time ◽  
Fermion Field ◽  
Chameleon Mechanism ◽  
Expansion Of The Universe ◽  
Stable Solutions ◽  
The Universe

We study the cosmological dynamics of Brans-Dicke theory in which there are fermions with a coupling to BD scalar field as well as a self-interaction potential. The conditions that there exists a solution which is stable and represents a late-time accelerated expansion of the universe are found. It is shown that the late-time acceleration depends completely on the self-interaction of the fermion field if our investigation is restricted to the theory with positive BD parameter ω. Provided a negative ω is allowed, there will be another two class of stable solutions describing late-time accelerated expansion of the universe. Besides, we find that chameleon mechanism will be possessed in our theory when a suitable self-interaction of fermion field is considered.

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