scholarly journals Evaluation of the Cosmological Constant in Inflation with a Massive Nonminimal Scalar Field

2015 ◽  
Vol 2015 ◽  
pp. 1-7
Author(s):  
Jung-Jeng Huang
Keyword(s):  
Scalar Field ◽  
Dispersion Relation ◽  
Energy Density ◽  
Cosmological Constant ◽  
Vacuum Energy ◽  
Vacuum State ◽  
Energy Scale ◽  
Quantum Evolution ◽  
Vacuum Energy Density ◽  
De Sitter

In Schrödinger picture we study the possible effects of trans-Planckian physics on the quantum evolution of massive nonminimally coupled scalar field in de Sitter space. For the nonlinear Corley-Jacobson type dispersion relations with quartic or sextic correction, we obtain the time evolution of the vacuum state wave functional during slow-roll inflation and calculate explicitly the corresponding expectation value of vacuum energy density. We find that the vacuum energy density is finite. For the usual dispersion parameter choice, the vacuum energy density for quartic correction to the dispersion relation is larger than for sextic correction, while for some other parameter choices, the vacuum energy density for quartic correction is smaller than for sextic correction. We also use the backreaction to constrain the magnitude of parameters in nonlinear dispersion relation and show how the cosmological constant depends on the parameters and the energy scale during the inflation at the grand unification phase transition.

IMPORTANT REMARKS ON (ANTI) de SITTER SPACES AND THE COSMOLOGICAL CONSTANT

2006 ◽  
Vol 21 (35) ◽  
pp. 2685-2701 ◽  
Author(s):  
CARLOS CASTRO
Keyword(s):  
Energy Density ◽  
Cosmological Constant ◽  
Vacuum Energy ◽  
Radial Function ◽  
Vacuum Energy Density ◽  
De Sitter ◽  
Cosmological Constant Problem ◽  
Natural Explanation ◽  
Observable Universe ◽  
Weyl Geometry

A class of proper and novel generalizations of the (anti) de Sitter solutions (parametrized by a family of radial functions R(r)) are presented that could provide a very plausible resolution of the cosmological constant problem along with a natural explanation of the ultraviolet/infrared (uv/ir) entanglement required to solve this problem. A nonvanishing value of the vacuum energy density of the order of [Formula: see text] is derived in agreement with the experimental observations. The presence of the radial function R(r) is instrumental to understand why the cosmological constant is not zero and why it is so tiny. The correct lower estimate of the mass of the observable universe related to the Dirac–Eddington's large number N = 1080 is also obtained. Finally we present our most recent findings of how Weyl Geometry via a Brans–Dicke scalar field solves the riddle of dark energy in addition to providing another derivation of the vacuum energy density.

scholarly journals COSMOLOGICAL CONSTANT IN A QUANTUM FLUID MODEL

2011 ◽  
Vol 20 (13) ◽  
pp. 2497-2506
Author(s):  
J. A. SÁNCHEZ-MONROY ◽  
C. J. QUIMBAY
Keyword(s):  
Energy Density ◽  
Cosmological Constant ◽  
Vacuum Energy ◽  
Fluid Model ◽  
Vacuum State ◽  
Vacuum Energy Density ◽  
Back Reaction ◽  
Quantum Fluid ◽  
Spacetime Curvature ◽  
Higher Order Corrections

Possible analogies between vacuum state and quantum fluid provide a model to study vacuum energy density induced by thermal corrections, spacetime curvature, boundary conditions and quantum back-reaction. We find that vacuum energy density in this quantum fluid model is not naturally of the order of the matter energy density. We show how higher-order corrections in quantum back-reaction can also contribute to vacuum energy density, and how the cosmological expansion is a manifestation of a universe out of mechanical equilibrium. This last fact implies that simple thermodynamic arguments are not enough to explain the cosmological constant problem because the calculation of the associated vacuum energy density requires first the knowledge of the underlying microscopic physics of vacuum.

scholarly journals Decaying vacuum inflationary cosmologies: Searching for a complete scenario including curvature effects

2015 ◽  
Vol 24 (04) ◽  
pp. 1541006 ◽  
Author(s):  
J. A. S. Lima ◽  
E. L. D. Perico ◽  
G. J. M. Zilioti
Keyword(s):  
Energy Density ◽  
Vacuum Energy ◽  
Planck Scale ◽  
Energy Scale ◽  
Vacuum Energy Density ◽  
De Sitter ◽  
Curvature Effects ◽  
Curvature Parameter ◽  
Natural Solution ◽  
Cosmic History

We propose a large class of nonsingular cosmologies of arbitrary spatial curvature whose cosmic history is determined by a primeval dynamical Λ(t)-term. For all values of the curvature, the models evolve between two extreme de Sitter phases driven by the relic time-varying vacuum energy density. The transition from inflation to the radiation phase is universal and points to a natural solution of the graceful exit problem regardless of the values of the curvature parameter. The flat case recovers the scenario recently discussed in the literature [Perico et al., Phys. Rev. D88 (2013) 063531]. The early de Sitter phase is characterized by an arbitrary energy scale HI associated to the primeval vacuum energy density. If HI is fixed to be nearly the Planck scale, the ratio between the relic and the present observed vacuum energy density is ρvI/ρv0 ≃ 10118.

scholarly journals VACUUM SELECTION BY INFLATION AS THE ORIGIN OF THE DARK ENERGY

2002 ◽  
Vol 11 (10) ◽  
pp. 1603-1608 ◽  
Author(s):  
JUN'ICHI YOKOYAMA
Keyword(s):  
Dark Energy ◽  
Energy Density ◽  
Cosmological Constant ◽  
Vacuum Energy ◽  
Vacuum State ◽  
Field Configuration ◽  
Inflationary Cosmology ◽  
Vacuum Energy Density ◽  
Winding Number ◽  
Instanton Action

I propose a new mechanism to account for the observed tiny but finite dark energy in terms of a non-Abelian Higgs theory, which has infinitely many perturbative vacua characterized by a winding number, in the framework of inflationary cosmology. Inflation homogenizes field configuration and practically realizes a perturbative vacuum with vanishing winding number, which is expressed by a superposition of eigenstates of the Hamiltonian with different vacuum energy density. As a result, we naturally find a nonvanishing vacuum energy density with fairly large probability, under the assumption that the cosmological constant vanishes in some vacuum state. Since the predicted magnitude of dark energy is exponentially suppressed by the instanton action, we can fit observation without introducing any tiny parameters.

CP NONINVARIANCE AND AN EFFECTIVE COSMOLOGICAL CONSTANT: THE ENERGY DENSITY IN A PSEUDOSCALAR FIELD WHICH ARISES FROM A COSMOLOGICAL, SPONTANEOUSLY-BROKEN CHIRAL SYMMETRY

2004 ◽  
Vol 19 (39) ◽  
pp. 2899-2908 ◽  
Author(s):  
SAUL BARSHAY ◽  
GEORG KREYERHOFF
Keyword(s):  
Energy Density ◽  
Cosmological Constant ◽  
Chiral Symmetry ◽  
Vacuum Energy ◽  
Energy Scale ◽  
Vacuum Energy Density ◽  
Small Scale ◽  
Absolute Value ◽  
Effective Cosmological Constant ◽  
Residual Vacuum

We present and discuss the properties and the main results of a cosmological model with a spontaneously-broken chiral symmetry. The model contains and relates dynamically, two spin-zero fields. The scalar field can provide the dynamical basis for inflation in the early universe. The pseudoscalar, Goldstone field can provide an early, small residual vacuum energy density, the absolute value of which we estimate to be similar to the present, empirically small vacuum energy density. The small energy scale for this effective cosmological constant is estimated separately, by relating it dynamically to the empirical, small scale of neutrino mass. CP invariance is broken spontaneously. This provides a natural basis for the early generation of an antineutrino–neutrino asymmetry, whose magnitude we estimate, and find to be significant.

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 THE NATURE OF THE COSMOLOGICAL CONSTANT PROBLEM

2009 ◽  
Vol 24 (08n09) ◽  
pp. 1545-1548 ◽  
Author(s):  
M. D. MAIA ◽  
A. J. S. CAPISTRANO ◽  
E. M. MONTE
Keyword(s):  
General Relativity ◽  
Gravitational Field ◽  
Energy Density ◽  
Cosmological Constant ◽  
Ground State ◽  
Vacuum Energy ◽  
Dimensional Space ◽  
Brane World ◽  
Vacuum Energy Density ◽  
Cosmological Constant Problem

General relativity postulates the Minkowski space-time as the standard (flat) geometry against which we compare all curved space-times and also as the gravitational ground state where particles, quantum fields and their vacua are defined. On the other hand, experimental evidences tell that there exists a non-zero cosmological constant, which implies in a deSitter ground state, which not compatible with the assumed Minkowski structure. Such inconsistency is an evidence of the missing standard of curvature in Riemann's geometry, which in general relativity manifests itself in the form of the cosmological constant problem. We show how the lack of a curvature standard in Riemann's geometry can be fixed by Nash's theorem on metric perturbations. The resulting higher dimensional gravitational theory is more general than general relativity, similar to brane-world gravity, but where the propagation of the gravitational field along the extra dimensions is a mathematical necessity, rather than a postulate. After a brief introduction to Nash's theorem, we show that the vacuum energy density must remain confined to four-dimensional space-times, but the cosmological constant resulting from the contracted Bianchi identity represents a gravitational term which is not confined. In this case, the comparison between the vacuum energy and the cosmological constant in general relativity does not make sense. Instead, the geometrical fix provided by Nash's theorem suggests that the vacuum energy density contributes to the perturbations of the gravitational field.

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