THE ORIGIN OF SCALE–SCALE CORRELATIONS OF THE DENSITY PERTURBATIONS DURING INFLATION

1999 ◽  
Vol 08 (06) ◽  
pp. 731-738
Author(s):  
LI-ZHI FANG ◽  
WOLUNG LEE ◽  
JESÚS PANDO
Keyword(s):  
Density Perturbation ◽  
Time Dependent ◽  
Long Time Tails ◽  
Long Wavelength ◽  
Testable Prediction ◽  
Slow Roll ◽  
Time Correlations ◽  
Long Time ◽  
Density Perturbations ◽  
Slow Roll Inflation

We show that scale–scale correlations are a generic feature of slow-roll inflation theories. These correlations result from the long-time tails characteristic of the time dependent correlations because the long wavelength density perturbation modes are diffusion-like. A relationship between the scale–scale correlations and time-correlations is established providing a way to reveal the time correlations of the perturbations during inflation. This mechanism provides for a testable prediction that the scale–scale correlations at two different spatial points will vanish.

scholarly journals Intermittency, nonlinear dynamics and dissipation in the solar wind and astrophysical plasmas

2015 ◽  
Vol 373 (2041) ◽  
pp. 20140154 ◽  
Author(s):  
W. H. Matthaeus ◽  
Minping Wan ◽  
S. Servidio ◽  
A. Greco ◽  
K. T. Osman ◽  
...  
Keyword(s):  
Essential Feature ◽  
Dissipation Function ◽  
Astrophysical Plasmas ◽  
Structure Generation ◽  
Inverse Cascade ◽  
Time Correlations ◽  
Basic Physics ◽  
Long Time ◽  
Carry Over ◽  
Approach To Steady State

An overview is given of important properties of spatial and temporal intermittency, including evidence of its appearance in fluids, magnetofluids and plasmas, and its implications for understanding of heliospheric plasmas. Spatial intermittency is generally associated with formation of sharp gradients and coherent structures. The basic physics of structure generation is ideal, but when dissipation is present it is usually concentrated in regions of strong gradients. This essential feature of spatial intermittency in fluids has been shown recently to carry over to the realm of kinetic plasma, where the dissipation function is not known from first principles. Spatial structures produced in intermittent plasma influence dissipation, heating, and transport and acceleration of charged particles. Temporal intermittency can give rise to very long time correlations or a delayed approach to steady-state conditions, and has been associated with inverse cascade or quasi-inverse cascade systems, with possible implications for heliospheric prediction.

Experimental observation of “long time tails”?

1976 ◽  
Vol 55 (7) ◽  
pp. 391-392 ◽  
Author(s):  
J.P. Boon ◽  
A. Bouiller
Keyword(s):  
Experimental Observation ◽  
Long Time Tails ◽  
Long Time

scholarly journals Generalized slow-roll inflation

2000 ◽  
Vol 269 (4) ◽  
pp. 209-213 ◽  
Author(s):  
Valerio Faraoni
Keyword(s):  
Slow Roll ◽  
Slow Roll Inflation

Upstream motions in stratified flow

1988 ◽  
Vol 187 ◽  
pp. 487-506 ◽  
Author(s):  
I. P. Castro ◽  
W. H. Snyder
Keyword(s):  
Body Height ◽  
Three Dimensional ◽  
Time Dependent ◽  
Experimental Measurements ◽  
Two Dimensional ◽  
Towing Tank ◽  
First Order ◽  
Density Perturbations ◽  
Small Obstacle ◽  
Obstacle Height

In this paper experimental measurements of the time-dependent velocity and density perturbations upstream of obstacles towed through linearly stratified fluid are presented. Attention is concentrated on two-dimensional obstacles which generate turbulent separated wakes at Froude numbers, based on velocity and body height, of less than 0.5. The form of the upstream columnar modes is shown to be largely that of first-order unattenuating disturbances, which have little resemblance to the perturbations described by small-obstacle-height theories. For two-dimensional obstacles the disturbances are similar to those found by Wei, Kao & Pao (1975) and it is shown that provided a suitable obstacle drag coefficient is specified, the lowest-order modes (at least) are quantitatively consistent with the results of the Oseen inviscid model.Discussion of some results of similar measurements upstream of three-dimensional obstacles, the importance of towing tank endwalls and the relevance of the Foster & Saffman (1970) theory for the limit of zero Froude number is also included.

scholarly journals THE N-TACHYON ASSISTED INFLATION

2007 ◽  
Vol 22 (36) ◽  
pp. 2737-2748 ◽  
Author(s):  
HARVENDRA SINGH
Keyword(s):  
Open String ◽  
Slow Roll ◽  
Slow Roll Inflation

In continuation of the papers hep-th/0505012 and hep-th/0508101 we investigate the consequences when N open-string tachyons roll down simultaneously. We demonstrate that the N-tachyon system coupled to gravity does indeed give rise to the assisted slow-roll inflation.

scholarly journals NATURAL SLOW-ROLL INFLATION

1996 ◽  
Vol 11 (08) ◽  
pp. 631-646 ◽  
Author(s):  
R.F. LANGBEIN ◽  
K. LANGFELD ◽  
H. REINHARDT ◽  
L. von SMEKAL
Keyword(s):  
Phase Change ◽  
Early Universe ◽  
Slow Roll ◽  
Slow Roll Inflation

It is shown that the nonperturbative dynamics of a phase change to the nontrivial phase of λφ4-theory in the early universe can give rise to slow-rollover inflation without recourse to unnaturally small couplings.

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