Conditions for generating scale-invariant density perturbations

2004 ◽  
Vol 69 (10) ◽  
Author(s):  
Steven Gratton ◽  
Justin Khoury ◽  
Paul J. Steinhardt ◽  
Neil Turok
Keyword(s):  
Invariant Density ◽  
Scale Invariant ◽  
Density Perturbations

scholarly journals GENERATION OF SCALE INVARIANT DENSITY PERTURBATIONS IN A CONFORMALLY INVARIANT INERT HIGGS DOUBLET MODEL

2013 ◽  
Vol 28 (19) ◽  
pp. 1350094 ◽  
Author(s):  
MOUMITA DAS ◽  
SUBHENDRA MOHANTY
Keyword(s):  
Scalar Potential ◽  
Higgs Field ◽  
Density Perturbation ◽  
Coupled System ◽  
Higgs Doublet ◽  
Invariant Density ◽  
Scale Invariant ◽  
Conformally Invariant ◽  
Density Perturbations ◽  
Doublet Model

If a Higgs field is conformally coupled to gravity, then it can give rise to the scale invariant density perturbations. We make use of this result in a realistic inert Higgs doublet model, where we have a pair of Higgs doublets conformally coupled to the gravity in the early universe. The perturbation of the inert Higgs is shown to be the scale invariant. This gives rise to the density perturbation observed through CMB by its couplings to the standard model Higgs and the subsequent decay. Loop corrections of this conformally coupled system gives rise to electroweak symmetry breaking. We constrain the couplings of the scalar potential by comparing with the amplitude and spectrum of CMB anisotropy measured by WMAP and this model leads to a prediction for the masses of the lightest Higgs and the other scalars.

scholarly journals Non-scale-invariant density perturbations from chaotic extended inflation

1992 ◽  
Vol 45 (6) ◽  
pp. 1961-1970 ◽  
Author(s):  
Silvia Mollerach ◽  
Sabino Matarrese
Keyword(s):  
Invariant Density ◽  
Scale Invariant ◽  
Density Perturbations

scholarly journals Scale invariant density perturbations from cyclic cosmology

2016 ◽  
Vol 31 (13) ◽  
pp. 1650076 ◽  
Author(s):  
Paul Howard Frampton
Keyword(s):  
Large Scale ◽  
Quantum Fluctuations ◽  
Large Scale Structure ◽  
Density Fluctuations ◽  
Scale Structure ◽  
Invariant Density ◽  
Scale Invariant ◽  
Density Perturbations

It is shown how quantum fluctuations of the radiation during the contraction era of a comes back empty (CBE) cyclic cosmology can provide density fluctuations which re-enter the horizon during the subsequent expansion era and at lowest order are scale invariant, in a Harrison–Zel’dovich–Peebles sense. It is necessary to be consistent with observations of large scale structure.

scholarly journals Bose–Einstein condensation as an alternative to inflation

2015 ◽  
Vol 24 (12) ◽  
pp. 1544001 ◽  
Author(s):  
Saurya Das
Keyword(s):  
Ground State ◽  
Large Scale ◽  
Small Mass ◽  
Einstein Condensate ◽  
Einstein Condensation ◽  
Scale Invariant ◽  
Bose Einstein Condensate ◽  
Density Perturbations ◽  
Bose Einstein ◽  
The Universe

It was recently shown that gravitons with a very small mass should have formed a Bose–Einstein condensate (BEC) in the very early universe, whose density and quantum potential can account for the dark matter (DM) and dark energy (DE) in the universe respectively. Here, we show that the condensation can also naturally explain the observed large scale homogeneity and isotropy of the universe. Furthermore, gravitons continue to fall into their ground state within the condensate at every epoch, accounting for the observed flatness of space at cosmological distance scales. Finally, we argue that the density perturbations due to quantum fluctuations within the condensate give rise to a scale invariant spectrum. This therefore provides a viable alternative to inflation, which is not associated with the well-known problems associated with the latter.

The growth of structure

2021 ◽  
pp. 379-397
Author(s):  
Andrew M. Steane
Keyword(s):  
Gravitational Collapse ◽  
Acoustic Oscillations ◽  
Scale Invariant ◽  
Small Perturbations ◽  
Density Perturbations ◽  
Structure Equations ◽  
Jeans Instability ◽  
Baryon Acoustic Oscillations

The growth of structure by gravitational collapse from initially small perturbations is described. The Jeans instability is calculated. The structure equations are obtained and solved in various cases (radiation-dominated, matter-dominated and others) via a linearized treatment. Hence the main features of the growth of density perturbations are obtained. The observed spectrum in the present is used to infer the primordial spectrum. The scale-invariant (Harrison-Zol’dovich) spectrum is described. The process of baryon acoustic oscillations is outlined and the sound horizon is defined. The chapter concludes with brief notes on galaxy formatiom.

scholarly journals COSMOLOGICAL PREDICTIONS FROM THE MISNER BRANE

2003 ◽  
Vol 12 (06) ◽  
pp. 985-1014
Author(s):  
PEDRO F. GONZÁLEZ-DÍAZ
Keyword(s):  
Black Hole ◽  
Semiclassical Approximation ◽  
Integral Approach ◽  
De Sitter ◽  
Scale Invariant ◽  
Brane Cosmology ◽  
Dimensional Gravity ◽  
Density Perturbations ◽  
Spacetime Metric ◽  
Inflationary Models

Within the spirit of five-dimensional gravity in the Randall-Sundrum scenario, in this paper we consider cosmological and gravitational implications induced by forcing the spacetime metric to satisfy a Misner-like symmetry. We first show that in the resulting Misner-brane framework the Friedmann metric for a radiation dominated flat universe and the Schwarzschild or anti-de Sitter black hole metrics are exact solutions on the branes, but the model cannot accommodate any inflationary solution. The horizon and flatness problems can however be solved in Misner-brane cosmology by causal and noncausal communications through the extra dimension between distant regions which are outside the horizon. Based on a semiclassical approximation to the path-integral approach, we have calculated the quantum state of the Misner-brane universe and the quantum perturbations induced on its metric by brane propagation along the fifth direction. We have then considered testable predictions from our model. These include a scale-invariant spectrum of density perturbations whose amplitude can be naturally accommodated to the required value 10-5-10-6, and a power spectrum of CMB anisotropies whose acoustic peaks are at the same sky angles as those predicted by inflationary models, but having much smaller secondary-peak intensities. These predictions seem to be compatible with COBE and recent Boomerang and Maxima measurements.

Sign in / Sign up

Export Citation Format

Share Document