scholarly journals Features of the inflaton potential and the power spectrum of cosmological perturbations

2021 ◽  
Vol 104 (2) ◽  
Author(s):  
K. Kefala ◽  
G. P. Kodaxis ◽  
I. D. Stamou ◽  
N. Tetradis
Keyword(s):  
Power Spectrum ◽  
Cosmological Perturbations

BOUNCING AND QUANTUM THEORY

2011 ◽  
Vol 03 ◽  
pp. 183-194
Author(s):  
NELSON PINTO-NETO
Keyword(s):  
Wave Function ◽  
Quantum Theory ◽  
Power Spectrum ◽  
Quantum Cosmology ◽  
Cosmological Perturbations ◽  
Simple Equations ◽  
The Universe ◽  
Inflationary Models

In this contribution I will present a review about bouncing models arriving from quantum cosmology and show how one can describe the evolution of quantum cosmological perturbations on them. I will discuss the important role played by the choice of the precise quantum theory one selects to interpret the wave function of the Universe in order to obtain simple equations for the evolution of quantum perturbations on these quantum cosmological backgrounds. I will present the predictions of these models concerning the power spectrum of cosmological perturbations and how they can be compared with the usual results obtained from inflationary models. Finally, I will present the new implications of these results for quantum theory.

scholarly journals A SEMI-ANALYTICAL APPROACH TO PERTURBATIONS IN MUTATED HILLTOP INFLATION

2012 ◽  
Vol 21 (02) ◽  
pp. 1250017 ◽  
Author(s):  
BARUN KUMAR PAL ◽  
SUPRATIK PAL ◽  
B. BASU
Keyword(s):  
Power Spectrum ◽  
Cosmic Microwave Background ◽  
Numerical Computation ◽  
Analytical Approach ◽  
Cosmological Perturbations ◽  
Microwave Background ◽  
Analytical Treatment ◽  
Angular Power Spectrum

We study cosmological perturbations and observational aspects for mutated hilltop model of inflation. Employing mostly analytical treatment, we evaluate observable parameters during inflation as well as post-inflationary perturbations. This further leads to exploring observational aspects related to cosmic microwave background (CMB) radiation. This semi-analytical treatment reduces complications related to numerical computation to some extent for studying the different phenomena related to CMB angular power spectrum for mutated hilltop inflation.

scholarly journals Scalar cosmological perturbations in M-theory with higher-derivative corrections

2020 ◽  
Vol 2020 (11) ◽  
Author(s):  
Kazuho Hiraga ◽  
Yoshifumi Hyakutake
Keyword(s):  
Power Spectrum ◽  
Equations Of Motion ◽  
Cosmological Perturbations ◽  
Curvature Perturbation ◽  
Linearized Equations ◽  
Higher Derivative ◽  
Expansion Of The Universe ◽  
M Theory ◽  
The Universe ◽  
Scalar Perturbations

Abstract We investigate the inflationary expansion of the universe induced by higher-curvature corrections in M-theory. The inflationary evolution of the geometry is discussed in K. Hiraga and Y. Hyakutake, Prog. Theor. Exp. Phys. 2018, 113B03 (2018), which we follow to analyze metric perturbations around the background. We especially focus on scalar perturbations and analyze linearized equations of motion for the scalar perturbations. By solving these equations explicitly, we evaluate the power spectrum of the curvature perturbation. The scalar spectrum index is estimated under some assumptions, and we show that it becomes close to 1.

BOUNCING AND QUANTUM THEORY

2011 ◽  
Vol 26 (22) ◽  
pp. 3801-3812
Author(s):  
NELSON PINTO-NETO
Keyword(s):  
Wave Function ◽  
Quantum Theory ◽  
Power Spectrum ◽  
Quantum Cosmology ◽  
Cosmological Perturbations ◽  
Simple Equations ◽  
The Universe ◽  
Inflationary Models

In this contribution I will present a review about bouncing models arriving from quantum cosmology and show how one can describe the evolution of quantum cosmological perturbations on them. I will discuss the important role played by the choice of the precise quantum theory one selects to interpret the wave function of the Universe in order to obtain simple equations for the evolution of quantum perturbations on these quantum cosmological backgrounds. I will present the predictions of these models concerning the power spectrum of cosmological perturbations and how they can be compared with the usual results obtained from inflationary models. Finally, I will present the new implications of these results for quantum theory.

The on-line use of histogram data for high-speed correction and alignment of electron microscope images

1984 ◽  
Vol 42 ◽  
pp. 556-557
Author(s):  
William Krakow
Keyword(s):  
Power Spectrum ◽  
High Speed ◽  
Direct Memory Access ◽  
Digital Television ◽  
Contrast Transfer Function ◽  
The Past ◽  
High Resolution Tem ◽  
On Line ◽  
Correction Of Astigmatism ◽  
The Fourier Transform

In the past few years on-line digital television frame store devices coupled to computers have been employed to attempt to measure the microscope parameters of defocus and astigmatism. The ultimate goal of such tasks is to fully adjust the operating parameters of the microscope and obtain an optimum image for viewing in terms of its information content. The initial approach to this problem, for high resolution TEM imaging, was to obtain the power spectrum from the Fourier transform of an image, find the contrast transfer function oscillation maxima, and subsequently correct the image. This technique requires a fast computer, a direct memory access device and even an array processor to accomplish these tasks on limited size arrays in a few seconds per image. It is not clear that the power spectrum could be used for more than defocus correction since the correction of astigmatism is a formidable problem of pattern recognition.

Log-log scale roughness spectroscopy of surfaces

1993 ◽  
Vol 51 ◽  
pp. 224-225
Author(s):  
P. Fraundorf ◽  
B. Armbruster
Keyword(s):  
Power Spectrum ◽  
Autocorrelation Function ◽  
Power Spectra ◽  
Scanning Force Microscopy ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Force Microscopy ◽  
Scanning Force ◽  
Lateral Structure ◽  
Scale Roughness

Optical interferometry, confocal light microscopy, stereopair scanning electron microscopy, scanning tunneling microscopy, and scanning force microscopy, can produce topographic images of surfaces on size scales reaching from centimeters to Angstroms. Second moment (height variance) statistics of surface topography can be very helpful in quantifying “visually suggested” differences from one surface to the next. The two most common methods for displaying this information are the Fourier power spectrum and its direct space transform, the autocorrelation function or interferogram. Unfortunately, for a surface exhibiting lateral structure over several orders of magnitude in size, both the power spectrum and the autocorrelation function will find most of the information they contain pressed into the plot’s origin. This suggests that we plot power in units of LOG(frequency)≡-LOG(period), but rather than add this logarithmic constraint as another element of abstraction to the analysis of power spectra, we further recommend a shift in paradigm.

INSTABILITIES IN THE POWER SPECTRUM OF MODE-LOCKED SEMICONDUCTOR LASERS

1988 ◽  
Vol 49 (C2) ◽  
pp. C2-405-C2-408 ◽  
Author(s):  
D. BAUMS ◽  
M. SERÉNYI ◽  
W. ELSÄSSER ◽  
E. O. GÖBEL
Keyword(s):  
Power Spectrum ◽  
Semiconductor Lasers
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