scholarly journals Time dependent couplings as observables in de Sitter space

2014 ◽  
Vol 29 (08) ◽  
pp. 1430016 ◽  
Author(s):  
Hiroyuki Kitamoto ◽  
Yoshihisa Kitazawa
Keyword(s):  
Physical Mechanism ◽  
Quantum Effect ◽  
De Sitter Space ◽  
Time Dependent ◽  
General Covariance ◽  
De Sitter ◽  
Scale Invariant ◽  
Logarithmic Corrections ◽  
Slow Roll ◽  
The One

We summarize and expand our investigations concerning the soft graviton effects on microscopic matter dynamics in de Sitter space. The physical couplings receive IR logarithmic corrections which are sensitive to the IR cutoff at the one-loop level. The scale invariant spectrum in the gravitational propagator at the super-horizon scale is the source of the de Sitter symmetry breaking. The quartic scalar, Yukawa and gauge couplings become time dependent and diminish with time. In contrast, the Newton's constant increases with time. We clarify the physical mechanism behind these effects in terms of the conformal mode dynamics in analogy with 2d quantum gravity. We show that they are the inevitable consequence of the general covariance and lead to gauge invariant predictions. We construct a simple model in which the cosmological constant is self-tuned to vanish due to UV–IR mixing effect. We also discuss phenomenological implications such as decaying Dark Energy and SUSY breaking at the inflation era. The quantum effect alters the classical slow roll picture in general, if the tensor-to-scalar ratio r is as small as 0.01.

scholarly journals Phase Transition and Entropy Force between Two Horizons in (n+2)-Dimensional de Sitter Space

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Yang Zhang ◽  
Wen-qi Wang ◽  
Yu-bo Ma ◽  
Jun Wang
Keyword(s):  
Phase Transition ◽  
Black Holes ◽  
Physical Mechanism ◽  
De Sitter Space ◽  
Space Time ◽  
Thermodynamic Quantities ◽  
De Sitter ◽  
Time Dimension ◽  
Cosmic Expansion

In this paper, the effect of the space-time dimension on effective thermodynamic quantities in (n+2)-dimensional Reissner-Nordstrom-de Sitter space has been studied. Based on derived effective thermodynamic quantities, conditions for the phase transition are obtained. The result shows that the accelerating cosmic expansion can be attained by the entropy force arisen from the interaction between horizons of black holes and our universe, which provides a possible way to explain the physical mechanism for the accelerating cosmic expansion.

scholarly journals QUANTUM KALB–RAMOND FIELD IN D-DIMENSIONAL DE SITTER SPACE–TIMES

2013 ◽  
Vol 28 (05n06) ◽  
pp. 1350011
Author(s):  
G. ALENCAR ◽  
I. GUEDES ◽  
R. R. LANDIM ◽  
R. N. COSTA FILHO
Keyword(s):  
Exact Solution ◽  
Wave Function ◽  
Quantum Theory ◽  
De Sitter Space ◽  
Equation Of Motion ◽  
Time Dependent ◽  
De Sitter ◽  
Sitter Background ◽  
Dynamic Invariant ◽  
Math Phys

In this work, we investigate the quantum theory of the Kalb–Ramond fields propagating in D-dimensional de Sitter space–times using the dynamic invariant method developed by Lewis and Riesenfeld [J. Math. Phys.10, 1458 (1969)] to obtain the solution of the time-dependent Schrödinger equation. The wave function is written in terms of a c-number quantity satisfying the Milne–Pinney equation, whose solution can be expressed in terms of two independent solutions of the respective equation of motion. We obtain the exact solution for the quantum Kalb–Ramond field in the de Sitter background and discuss its relation with the Cremmer–Scherk–Kalb–Ramond model.

scholarly journals De Sitter entropy as holographic entanglement entropy

2021 ◽  
Author(s):  
Nikolaos Tetradis
Keyword(s):  
Effective Action ◽  
Degrees Of Freedom ◽  
Entanglement Entropy ◽  
De Sitter Space ◽  
Conformal Anomaly ◽  
Dual Theory ◽  
De Sitter ◽  
Logarithmic Corrections ◽  
Holographic Entanglement Entropy ◽  
Gravitational Entropy

We review the results of refs. [1,2], in which the entanglement entropy in spaces with horizons, such as Rindler or de Sitter space, is computed using holography. This is achieved through an appropriate slicing of anti-de Sitter space and the implementation of a UV cutoff. When the entangling surface coincides with the horizon of the boundary metric, the entanglement entropy can be identified with the standard gravitational entropy of the space. For this to hold, the effective Newton's constant must be defined appropriately by absorbing the UV cutoff. Conversely, the UV cutoff can be expressed in terms of the effective Planck mass and the number of degrees of freedom of the dual theory. For de Sitter space, the entropy is equal to the Wald entropy for an effective action that includes the higher-curvature terms associated with the conformal anomaly. The entanglement entropy takes the expected form of the de Sitter entropy, including logarithmic corrections.

scholarly journals The inflationary wavefunction from analyticity and factorization

2021 ◽  
Vol 2021 (12) ◽  
pp. 018
Author(s):  
David Meltzer
Keyword(s):  
Analytic Continuation ◽  
De Sitter Space ◽  
Conformal Group ◽  
Tree Level ◽  
Late Time ◽  
De Sitter ◽  
Scale Invariant ◽  
Arbitrary Mass ◽  
Lower Point ◽  
Finite Sum

Abstract We study the analytic properties of tree-level wavefunction coefficients in quasi-de Sitter space. We focus on theories which spontaneously break dS boost symmetries and can produce significant non-Gaussianities. The corresponding inflationary correlators are (approximately) scale invariant, but are not invariant under the full conformal group. We derive cutting rules and dispersion formulas for the late-time wavefunction coefficients by using factorization and analyticity properties of the dS bulk-to-bulk propagator. This gives a unitarity method which is valid at tree-level for general n-point functions and for fields of arbitrary mass. Using the cutting rules and dispersion formulas, we are able to compute n-point functions by gluing together lower-point functions. As an application, we study general four-point, scalar exchange diagrams in the EFT of inflation. We show that exchange diagrams constructed from boost-breaking interactions can be written as a finite sum over residues. Finally, we explain how the dS identities used in this work are related by analytic continuation to analogous identities in Anti-de Sitter space.

scholarly journals SPONTANEOUS DECAY OF THE EFFECTIVE COSMOLOGICAL CONSTANT

1998 ◽  
Vol 13 (07) ◽  
pp. 571-580 ◽  
Author(s):  
MURAT ÖZER ◽  
M. O. TAHA
Keyword(s):  
Cosmological Constant ◽  
De Sitter Space ◽  
Space Time ◽  
Time Dependent ◽  
Spontaneous Decay ◽  
Quantum Fields ◽  
De Sitter ◽  
Initial Value ◽  
Effective Time ◽  
Effective Cosmological Constant

We discuss the notion that quantum fields may induce an effective time-dependent cosmological constant which decays from a large initial value. It is shown that such cosmological models are viable in a non-de Sitter space–time.

scholarly journals ON VACUUM DENSITY, THE INITIAL SINGULARITY AND DARK ENERGY

2009 ◽  
Vol 18 (14) ◽  
pp. 2343-2349 ◽  
Author(s):  
SAULO CARNEIRO ◽  
REZA TAVAKOL
Keyword(s):  
Phase Transition ◽  
Vacuum Energy ◽  
Field Potential ◽  
Scalar Fields ◽  
Vacuum Energy Density ◽  
De Sitter ◽  
Scale Invariant ◽  
Standard Cosmology ◽  
Slow Roll ◽  
Free Fields

Standard cosmology poses a number of important questions. Apart from its singular origin, it possesses early and late accelerating phases required to account for observations. The vacuum energy has been considered as a possible way to resolve some of these questions. The vacuum energy density induced by free fields in an early de Sitter phase has earlier been estimated to be proportional to H4, while more recently it has been suggested that the QCD condensate induces a term proportional to H at late times. These results have been employed in models which are nonsingular and inflationary at early times and accelerating at late times. Here we cast these models in terms of scalar fields and study the corresponding spectrum of primordial perturbations. At early times the spectrum is found to be not scale-invariant, thus implying that slow roll inflation is still required after the phase transition induced by the vacuum. At late times the corresponding scalar field potential is harmonic, with a mass of the order of the Hubble scale — a result that may be understood in the light of the holographic conjecture.

scholarly journals Cosmic magnetization out from the vacuum

2016 ◽  
Vol 31 (28) ◽  
pp. 1650165 ◽  
Author(s):  
Leonardo Campanelli
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Classical Limit ◽  
Large Scale ◽  
Quantum Effect ◽  
Wave Number ◽  
Scale Invariant ◽  
General Belief ◽  
Number Formula ◽  
The One

The large-scale magnetic fields we observe today in galaxies and galaxy clusters could be the result of a pure quantum effect taking place during inflation, to wit, the creation of particles (photons) out from the vacuum in a curved spacetime. We show that, whenever the conformal invariance of electromagnetism is broken during inflation, the actual magnetic field spectrum, in the classical limit, is given by [Formula: see text], where [Formula: see text] is the number of created photons with wave number [Formula: see text]. In particular, a scale-invariant magnetic field of order of 10[Formula: see text] G can emerge in the simplest model of cosmic magnetogenesis, the one where the inflaton is kinetically coupled to the photon. Moreover, and contrarily to the general belief, we show that such a model is free from the so-called strong-coupling and backreaction problems. This conclusion follows, indirectly, from the observation that post-inflationary electric currents, which in the literature are incorrectly supposed to freeze superhorizon magnetic fields after inflation, are indeed vanishing on superhorizon scales due to causality.

scholarly journals Einstein-singleton theory and its power spectra in de Sitter inflation

2016 ◽  
Vol 25 (14) ◽  
pp. 1650107
Author(s):  
Yun Soo Myung ◽  
Taeyoon Moon ◽  
Young-Jai Park
Keyword(s):  
Fourth Order ◽  
Power Spectra ◽  
Integral Function ◽  
De Sitter ◽  
Scale Invariant ◽  
Exponential Integral ◽  
Scalar Theory ◽  
Inflation Model ◽  
Slow Roll ◽  
Sitter Spacetime

We study the Einstein-singleton theory during de Sitter inflation since it provides a way to degenerate fourth-order scalar theory. We obtain an exact solution expressed in terms of the exponential-integral function by solving the degenerate fourth-order scalar equation in de Sitter spacetime. Furthermore, we find that its power spectrum blows negatively up in the superhorizon limit, while it is negatively scale-invariant in the subhorizon limit. This suggests that the Einstein-singleton theory contains the ghost-instability and thus, it is not suitable for developing a slow-roll inflation model.

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