scholarly journals SUPERSYMMETRIC BAROTROPIC FRW MODEL AND DARK ENERGY

2009 ◽  
Vol 24 (16) ◽  
pp. 1257-1266
Author(s):  
J. J. ROSALES ◽  
V. I. TKACH
Keyword(s):  
Dark Energy ◽  
Energy Density ◽  
Perfect Fluid ◽  
Vacuum Energy ◽  
Matter Field ◽  
Vacuum Energy Density ◽  
Square Root ◽  
Frw Universe ◽  
Frw Model

Using the superfield approach we construct the n = 2 supersymmetric Lagrangian for the FRW Universe with barotropic perfect fluid as matter field. The obtained supersymmetric algebra allowed us to take the square root of the Wheeler–DeWitt equation and solve the corresponding quantum constraint. This model leads to the relation between the vacuum energy density and the energy density of the dust matter.

scholarly journals Do we come from a quantum anomaly?

2019 ◽  
Vol 28 (14) ◽  
pp. 1944002 ◽  
Author(s):  
Spyros Basilakos ◽  
Nick E. Mavromatos ◽  
Joan Solà Peracaula
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Energy Density ◽  
Hubble Parameter ◽  
Vacuum Energy ◽  
Vacuum Energy Density ◽  
Quantum Anomaly ◽  
Inflationary Phase ◽  
Axion Field ◽  
The Universe

We present a string-based picture of the cosmological evolution in which (CP-violating) gravitational anomalies acting during the inflationary phase of the universe cause the vacuum energy density to “run” with the effective Hubble parameter squared, [Formula: see text], thanks to the axion field of the bosonic string multiplet. This leads to baryogenesis through leptogenesis with massive right-handed neutrinos. The generation of chiral matter after inflation helps in cancelling the anomalies in the observable radiation- and matter-dominated eras. The present era inherits the same “running vacuum” structure triggered during the inflationary time by the axion field. The current dark energy is thus predicted to be mildly dynamical, and dark matter should be made of axions. Paraphrasing Carl Sagan [ https://www.goodreads.com/author/quotes/10538.Carl_Sagan .]: we are all anomalously made from starstuff.

scholarly journals DARK ENERGY DENSITY IN MODELS WITH SPLIT SUPERSYMMETRY AND DEGENERATE VACUA

2012 ◽  
Vol 27 (11) ◽  
pp. 1250063 ◽  
Author(s):  
C. FROGGATT ◽  
R. NEVZOROV ◽  
H. B. NIELSEN
Keyword(s):  
Dark Energy ◽  
Energy Density ◽  
Cosmological Constant ◽  
Vacuum Energy ◽  
Susy Breaking ◽  
Vacuum Energy Density ◽  
Dark Energy Density ◽  
Hidden Sector ◽  
Split Supersymmetry ◽  
Breaking Scale

In N = 1 supergravity supersymmetric and nonsupersymmetric Minkowski vacua originating in the hidden sector can be degenerate. In the supersymmetric phase in flat Minkowski space, nonperturbative supersymmetry breakdown may take place in the observable sector, inducing a nonzero and positive vacuum energy density. Assuming that such a supersymmetric phase and the phase in which we live are degenerate, we estimate the value of the cosmological constant. We argue that the observed value of the dark energy density can be reproduced in the split SUSY scenario of SUSY breaking if the SUSY breaking scale is of order of 1010 GeV.

scholarly journals Dynamical dark energy with a constant vacuum energy density

2006 ◽  
Vol 636 (2) ◽  
pp. 80-85 ◽  
Author(s):  
B. Guberina ◽  
R. Horvat ◽  
H. Nikolić
Keyword(s):  
Dark Energy ◽  
Energy Density ◽  
Vacuum Energy ◽  
Vacuum Energy Density ◽  
Dynamical Dark Energy

Dark energy and dark matter as due to zero point energy

2012 ◽  
Vol 79 (3) ◽  
pp. 327-334 ◽  
Author(s):  
BO LEHNERT
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Energy Density ◽  
Vacuum Energy ◽  
Mass Density ◽  
Zero Point ◽  
Vacuum Energy Density ◽  
Zero Point Energy ◽  
Observable Universe ◽  
Point Energy

AbstractAn attempt is made to explain dark energy and dark matter of the expanding universe in terms of the zero point vacuum energy. This analysis is mainly limited to later stages of an observable nearly flat universe. It is based on a revised formulation of the spectral distribution of the zero point energy, for an ensemble in a defined statistical equilibrium having finite total energy density. The steady and dynamic states are studied for a spherical cloud of zero point energy photons. The ‘antigravitational’ force due to its pressure gradient then represents dark energy, and its gravitational force due to the energy density represents dark matter. Four fundamental results come out of the theory. First, the lack of emitted radiation becomes reconcilable with the concepts of dark energy and dark matter. Second, the crucial coincidence problem of equal orders of magnitude of mass density and vacuum energy density cannot be explained by the cosmological constant, but is resolved by the present variable concepts, which originate from the same photon gas balance. Third, the present approach becomes reconcilable with cosmical dimensions and with the radius of the observable universe. Fourth, the deduced acceleration of the expansion agrees with the observed one. In addition, mass polarity of a generalized gravitation law for matter and antimatter is proposed as a source of dark flow.

scholarly journals Quantum Mechanical Explanation for Dark energy, Cosmic Coincidence, Flatness, Age and Size of Universe

2019 ◽  
Author(s):  
Biswaranjan Dikshit
Keyword(s):  
Dark Energy ◽  
Energy Density ◽  
Vacuum Energy ◽  
Zero Point ◽  
Astronomical Observation ◽  
Vacuum Energy Density ◽  
Quantum Mechanical ◽  
Coincidence Problem ◽  
Dark Energy Density ◽  
Analytical Expression

In this paper, by taking the structure of universe to be a 3-sphere and assuming that the zero-point oscillator for all particles is same, we derive an analytical expression for  vacuum (or dark) energy density and eliminate the discrepancy of ~10123 between quantum mechanical prediction and astronomical observation. Thus, we solve the cosmological constant problem. Then, using the analytical expression of the dark energy, we derive the expression for non-vacuum contribution to energy density (ordinary/dark matter, radiation) and show that ratio between non-vacuum to vacuum energy is ~1/2, thus solving the cosmic coincidence problem which questions why the matter energy density is of the same order as the vacuum energy density. Finally, using the above expressions for energy density, observed flatness of space is explained, Hubble’s constant is proved to be exactly equal to the reciprocal of the age of universe and size of universe is estimated. The calculated age and radius of universe comes out to be ~14.4 billion years and ~50 billion light years respectively which match well with the astronomically observed data.

scholarly journals Application of Self-Similar Symmetry Model to Dark Energy

2018 ◽  
Author(s):  
Tomohide Sonoda
Keyword(s):  
Dark Energy ◽  
Energy Density ◽  
Vacuum Energy ◽  
Structure Constant ◽  
Fine Tuning ◽  
Theoretical Modelling ◽  
Fine Structure Constant ◽  
Vacuum Energy Density ◽  
Self Similar ◽  
The Universe

Recent observations of the dark energy density demonstrates the fine-tuning problem and challenges in theoretical modelling. In this study, we apply the self-similar symmetry (SSS) model, describing the hierarchical structure of the universe based on the Dirac large numbers hypothesis, to Einstein's cosmological term. We introduce a new similarity dimension, DB, in the SSS model. Using the DB SSS model, the cosmological constant, vacuum energy density, and Hubble parameter can be simply expressed as a function of the cosmic microwave background (CMB) temperature. We show that the initial value of the vacuum energy density at the creation of the universe is ρ0 = 1/8παf6, where αf is the fine structure constant. The results indicate that the CMB is the primary factor for the evolution of the universe, providing a unified understanding of the problems of naturalness.

scholarly journals DARK ENERGY AS A RELIC OF THE VACUUM-ENERGY CANCELLATION?

2008 ◽  
Vol 17 (01) ◽  
pp. 111-133
Author(s):  
ORCHIDEA MARIA LECIAN ◽  
GIOVANNI MONTANI
Keyword(s):  
Dark Energy ◽  
Cosmological Constant ◽  
Vacuum Energy ◽  
Gravitational Interaction ◽  
Friedmann Equation ◽  
Vacuum Energy Density ◽  
De Sitter ◽  
Frw Universe ◽  
First Case ◽  
Present Universe

We analyze the dynamical implications of an exponential Lagrangian density for the gravitational field, as referred to an isotropic FRW Universe. Then, we discuss the features of the generalized de Sitter phase, predicted by the new Friedmann equation. The existence of a consistent de Sitter solution arises only if the ratio between the vacuum energy density and that associated with the fundamental length of the theory acquires a tantalizing negative character. This choice allows us to explain the present Universe dark energy as a relic of the vacuum-energy cancellation due to the cosmological constant intrinsically contained in our scheme. The corresponding scalar-tensor description of the model is addressed too, and the behavior of the scalar field is analyzed for both negative and positive values of the cosmological term. In the first case, the Friedmann equation is studied both in vacuum and in the presence of external matter, while, in the second case, the quantum regime is approached in the framework of "repulsive" properties of the gravitational interaction, as described in recent issues in loop quantum cosmology. In particular, in the vacuum case, we find a pure non-Einsteinian effect, according to which a negative cosmological constant provides an accelerating de Sitter dynamics, in the region where the series expansion of the exponential term does not hold.

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