scholarly journals Primordial Dark Energy from a Condensate of Spinors in a 5D Vacuum

2013 ◽  
Vol 2013 ◽  
pp. 1-7
Author(s):  
Pablo Alejandro Sánchez ◽  
Mauricio Bellini
Keyword(s):  
Dark Energy ◽  
Energy Density ◽  
Inflationary Universe ◽  
De Sitter Spacetime ◽  
De Sitter ◽  
Dark Energy Density ◽  
Sitter Spacetime ◽  
Interesting Candidate ◽  
Expansion Of The Universe ◽  
The Universe

We explore the possibility that the expansion of the universe can be driven by a condensate of spinors which are free of interactions in a 5D relativistic vacuum defined in an extended de Sitter spacetime which is Riemann flat. The extra coordinate is considered as noncompact. After making a static foliation on the extra coordinate, we obtain an effective 4D (inflationary) de Sitter expansion which describes an inflationary universe. We found that the condensate of spinors studied here could be an interesting candidate to explain the presence of dark energy in the early universe. The dark energy density which we are talking about is poured into smaller subhorizon scales with the evolution of the inflationary expansion.

scholarly journals INFLATIONARY DARK ENERGY FROM A CONDENSATE OF SPINORS IN A 5D VACUUM

2013 ◽  
Vol 22 (12) ◽  
pp. 1342028 ◽  
Author(s):  
PABLO ALEJANDRO SÁNCHEZ ◽  
MAURICIO BELLINI
Keyword(s):  
Dark Energy ◽  
Early Universe ◽  
Inflationary Universe ◽  
De Sitter Spacetime ◽  
De Sitter ◽  
Physical Origin ◽  
Sitter Spacetime ◽  
Interesting Candidate ◽  
Expansion Of The Universe ◽  
The Universe

What is the physical origin of dark energy? Could this energy be originated by other fields than the inflaton? In this paper, we explore the possibility that the expansion of the universe can be driven by a condensate of spinors. These spinors are free of interactions on five-dimensional (5D) relativistic vacuum in an extended de Sitter spacetime. The extra coordinate is considered as noncompact. After making a static foliation on the extra coordinate, we obtain an effective four-dimensional (4D) (inflationary) de Sitter expansion which describes an inflationary universe. In view of our results, we conclude that the condensate of spinors here studied could be an interesting candidate to explain the presence of dark energy in the early universe.

scholarly journals LITTLE RIP COSMOLOGICAL MODELS WITH TIME-DEPENDENT EQUATION OF STATE

2012 ◽  
Vol 27 (36) ◽  
pp. 1250210 ◽  
Author(s):  
I. BREVIK ◽  
V. V. OBUKHOV ◽  
K. E. OSETRIN ◽  
A. V. TIMOSHKIN
Keyword(s):  
Dark Energy ◽  
Equation Of State ◽  
Cosmological Models ◽  
Time Dependent ◽  
De Sitter Spacetime ◽  
De Sitter ◽  
Energy Models ◽  
Sitter Spacetime ◽  
The Universe ◽  
Far Future

Specific dark energy models, leading to the Little Rip (LR) cosmology in the far future, are investigated. Conditions for the occurrence of LR in terms of the parameters present in the proposed equation of state for the dark energy cosmic fluid are studied. Estimates about the time needed before the occurrence of the small singularity in the standard LR model in which the universe approaches the de Sitter spacetime asymptotically, are given.

scholarly journals CAN THE EXISTENCE OF DARK ENERGY BE DIRECTLY DETECTED?

2009 ◽  
Vol 24 (18n19) ◽  
pp. 3426-3436 ◽  
Author(s):  
MARTIN L. PERL
Keyword(s):  
General Relativity ◽  
Dark Energy ◽  
Energy Density ◽  
Total Mass ◽  
Mass Density ◽  
Mass Energy ◽  
Dark Energy Density ◽  
Astronomical Observations ◽  
Expansion Of The Universe ◽  
The Universe

Over the last decade, astronomical observations show that the acceleration of the expansion of the universe is greater than expected from our understanding of conventional general relativity, the mass density of the visible universe, the size of the visible universe and other astronomical measurements. The additional expansion has been attributed to a variety of phenomenon that have been given the general name of dark energy. Dark energy in the universe seems to comprise a majority of the energy in the visible universe amounting to about three times the total mass energy. But locally the dark energy density is very small. However it is not zero. In this paper I describe the work of others and myself on the question of whether dark energy density can be directly detected. This is a work-in-progress and I have no answer at present.

scholarly journals Stringy Bubbles Solve de Sitter Troubles

Universe ◽  
2021 ◽  
Vol 7 (10) ◽  
pp. 363
Author(s):  
Per Berglund ◽  
Tristan Hübsch ◽  
Djordje Minic
Keyword(s):  
Bubble Nucleation ◽  
Recent Analysis ◽  
Mass Hierarchy ◽  
De Sitter Spacetime ◽  
De Sitter ◽  
Positive Cosmological Constant ◽  
Accelerating Expansion ◽  
Sitter Spacetime ◽  
Expansion Of The Universe ◽  
The Universe

Finding four-dimensional de Sitter spacetime solutions in string theory has been a vexing quest ever since the discovery of the accelerating expansion of the universe. Building on a recent analysis of bubble-nucleation in the decay of (false-vacuum) AdS backgrounds where the interfacing bubbles themselves exhibit a de Sitter geometry we show that this resonates strongly with a stringy cosmic brane construction that naturally provides for an exponential mass-hierarchy and the localization of both gravity and matter, in addition to an exponentially suppressed positive cosmological constant. Finally, we argue that these scenarios can be realized in terms of a generalization of a small resolution of a conifold singularity in the context of a (Lorentzian) Calabi–Yau 5-fold, where the isolated (Lorentzian) two complex dimensional Fano variety is a four-dimensional de Sitter spacetime.

scholarly journals Cosmological particle creation beyond de Sitter

2019 ◽  
Vol 28 (09) ◽  
pp. 1930015 ◽  
Author(s):  
Sujoy K. Modak
Keyword(s):  
Dark Energy ◽  
Particle Creation ◽  
Vacuum State ◽  
De Sitter Spacetime ◽  
De Sitter ◽  
Central Focus ◽  
Sitter Spacetime ◽  
Multi Stage ◽  
Classical Behavior ◽  
The Universe

Over the years, de Sitter spacetime has been a central focus in studies involving quantum fields, for its importance in the early and late expansion stages of the universe. While de Sitter spacetime closely mimics characteristics of the inflationary and dark energy dominated universe, it does not help to understand the radiation and matter dominated expansions. In this paper, we revisit some recent works involving the author which study gravitational particle creation beyond the de Sitter stage. Specifically, we present novel aspects of particle creation in the radiation dominated universe and then provide an analysis of time evolution of the primordial (Bunch–Davies) vacuum state, its particle excitation and quantum versus classical behavior of field modes in a multi-stage universe, comprising of (i) the inflationary de Sitter (ii) the radiation dominated and (iii) the late dark energy dominated stages.

scholarly journals ON DETERMINATION OF THE GEOMETRIC COSMOLOGICAL CONSTANT FROM THE OPERA EXPERIMENT OF SUPERLUMINAL NEUTRINOS

2012 ◽  
Vol 27 (11) ◽  
pp. 1250041 ◽  
Author(s):  
MU-LIN YAN ◽  
SEN HU ◽  
WEI HUANG ◽  
NENG-CHAO XIAO
Keyword(s):  
Dark Energy ◽  
Cosmological Constant ◽  
Fundamental Constant ◽  
Zero Point ◽  
De Sitter Spacetime ◽  
De Sitter ◽  
Point Energy ◽  
Sitter Spacetime ◽  
Effective Cosmological Constant

The recent OPERA experiment of superluminal neutrinos has deep consequences in cosmology. In cosmology a fundamental constant is the cosmological constant. From observations one can estimate the effective cosmological constant Λ eff which is the sum of the quantum zero point energy Λ dark energy and the geometric cosmological constant Λ. The OPERA experiment can be applied to determine the geometric cosmological constant Λ. It is the first study to distinguish the contributions of Λ and Λ dark energy from each other by experiment. The determination is based on an explanation of the OPERA experiment in the framework of Special Relativity with de Sitter spacetime symmetry.

scholarly journals Production of scalar particles in electric field on de Sitter expanding universe

2014 ◽  
Vol 29 (27) ◽  
pp. 1450138 ◽  
Author(s):  
Mihaela-Andreea Băloi
Keyword(s):  
Electric Field ◽  
Particle Production ◽  
Perturbation Methods ◽  
Transition Amplitude ◽  
Scalar Particle ◽  
De Sitter Spacetime ◽  
De Sitter ◽  
Scalar Particles ◽  
Sitter Spacetime ◽  
The Universe

The scalar particle production from vacuum in the presence of an electric field, on the de Sitter spacetime is studied. We use perturbation methods to define the transition amplitude. We obtain that the momentum is not conserved in this process. The probability density of pair production is computed by squaring the transition amplitude. Our graphical representations show that, the probability of scalar particle production was important only in the early stages of the universe, when Hubble's constant was very large in comparison with the mass of the particle. Also, we propose here a criterion for particle–antiparticle separation.

scholarly journals COSMO MSW EFFECT FOR MASS VARYING NEUTRINOS

2005 ◽  
Vol 20 (16) ◽  
pp. 1209-1215 ◽  
Author(s):  
PHAM QUANG HUNG ◽  
HEINRICH PÄS
Keyword(s):  
Dark Energy ◽  
Energy Density ◽  
Neutrino Mass ◽  
Neutrino Masses ◽  
Mass Variation ◽  
Level Crossing ◽  
Dark Energy Density ◽  
Astrophysical Neutrinos ◽  
The Universe

We consider neutrinos with varying masses which arise in scenarios relating neutrino masses to the dark energy density in the universe. We point out that the neutrino mass variation can lead to level crossing and thus a cosmo MSW effect, having dramatic consequences for the flavor ratio of astrophysical neutrinos.

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.

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