scholarly journals ON SIGNATURES OF SHORT DISTANCE PHYSICS IN THE COSMIC MICROWAVE BACKGROUND

2002 ◽  
Vol 17 (25) ◽  
pp. 3663-3680 ◽  
Author(s):  
ROBERT H. BRANDENBERGER ◽  
JÉRÔME MARTIN
Keyword(s):  
Excited State ◽  
Cosmic Microwave Background ◽  
Short Distance ◽  
The State ◽  
Inflationary Universe ◽  
Late Time ◽  
Cosmological Perturbations ◽  
Microwave Background ◽  
Hubble Radius

Following a self-contained review of the basics of the theory of cosmological perturbations, we discuss why the conclusions reached in the recent paper by Kaloper et al.1 are too pessimistic estimates of the amplitude of possible imprints of trans-Planckian (string) physics on the spectrum of cosmic microwave anisotropies in an inflationary universe. It is shown that the likely origin of large trans-Planckian effects on late time cosmological fluctuations comes from nonadiabatic evolution of the state of fluctuations while the wavelength is smaller than the Planck (string) scale, resulting in an excited state at the time that the wavelength crosses the Hubble radius during inflation.

Search for primordial symmetry breakings in CMB

2016 ◽  
Vol 31 (21) ◽  
pp. 1640003 ◽  
Author(s):  
Maresuke Shiraishi
Keyword(s):  
Symmetry Breaking ◽  
Cosmic Microwave Background ◽  
Observational Data ◽  
Theoretical Models ◽  
Space Representation ◽  
Harmonic Space ◽  
Late Time ◽  
Cosmological Perturbations ◽  
Microwave Background ◽  
Symmetry Breakings

There are possibilities to violate symmetries (e.g. parity and rotational invariance) in the primordial cosmological fluctuations. Such symmetry breakings can imprint very rich signatures in late-time phenomena, which may be possible to observe. Especially, Cosmic Microwave Background (CMB) will change its face drastically, corresponding to the symmetry-breaking types, since the harmonic-space representation is very sensitive to the statistical, spin and angular dependences of cosmological perturbations. Here, we discuss (1) general responses of CMB to the symmetry breakings, (2) some theoretical models creating interesting CMB signatures, and (3) aspects of the estimation from observational data.

scholarly journals Late Time Neutrino Masses, the LSND Experiment, and the Cosmic Microwave Background

2005 ◽  
Vol 94 (11) ◽  
Author(s):  
Z. Chacko ◽  
Lawrence J. Hall ◽  
Steven J. Oliver ◽  
Maxim Perelstein
Keyword(s):  
Cosmic Microwave Background ◽  
Neutrino Masses ◽  
Late Time ◽  
Microwave Background

INTRODUCING NEUTRINO MASS INTO UNIVERSAL EXTRA DIMENSION MODELS AND SOLVING COSMOLOGICAL PROBLEM

2007 ◽  
Vol 16 (05) ◽  
pp. 1571-1582
Author(s):  
SHIGEKI MATSUMOTO ◽  
JOE SATO ◽  
MASATO YAMANAKA ◽  
MASATO SENAMI
Keyword(s):  
Cosmic Microwave Background ◽  
Neutrino Mass ◽  
Extra Dimension ◽  
Branching Ratios ◽  
Neutrino Masses ◽  
Late Time ◽  
Universal Extra Dimension ◽  
Time Decay ◽  
Microwave Background ◽  
Cosmological Problem

Universal extra dimension (UED) models with right-handed neutrinos are studied. The introduction of the neutrinos makes us possible not only to describe Dirac neutrino masses but also to solve the cosmological problem called the KK graviton problem. This problem is essentially caused by the late time decay of a KK photon into a KK graviton and a photon, and it distorts the spectrum of the cosmic microwave background or the diffuse photon. We point out that, once we introduce right-handed neutrinos to UED models, the KK photon decays dominantly into neutrinos and does not emit a photon. We also discuss sub-dominant modes with a photon in the decay quantitatively, and show that their branching ratios are so small that the spectra are not distorted.

scholarly journals The polarimetric multi-frequency radio sources properties

2016 ◽  
Vol 25 (11) ◽  
pp. 1640005 ◽  
Author(s):  
Vincenzo Galluzzi ◽  
Marcella Massardi
Keyword(s):  
Power Spectrum ◽  
Cosmic Microwave Background ◽  
State Of The Art ◽  
The State ◽  
Radio Sources ◽  
Microwave Background ◽  
Complete Sample ◽  
Angular Power Spectrum ◽  
Extragalactic Radio Sources ◽  
Compact Array

The polarization properties of extragalactic radio sources at frequencies higher than [Formula: see text]GHz are still poorly constrained. However, their characterization would provide invaluable information about the physics of the emission processes and is crucial to estimate their contamination as foregrounds of the polarized Cosmic Microwave Background (CMB) angular power spectrum on scales [Formula: see text]arcmin. In this contribution, after summarizing the state-of-the-art of polarimetric observations in the millimetric wavelength bands, we present our observations of a complete sample of 53 sources with [Formula: see text]mJy carried out with the Australia Telescope Compact Array (ACTA) between [Formula: see text] and [Formula: see text]GHz. The analysis clearly shows that polarization properties cannot be simply inferred from total intensity ones, as the spectral behaviors of the two signals are typically different.

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 SHORT DISTANCE SIGNATURES IN COSMOLOGY: WHY NOT IN BLACK HOLES?

2004 ◽  
Vol 19 (09) ◽  
pp. 1395-1412 ◽  
Author(s):  
ROBERTO CASADIO ◽  
LAURA MERSINI
Keyword(s):  
Black Hole ◽  
Cosmic Microwave Background ◽  
Short Distance ◽  
New Physics ◽  
Physical Significance ◽  
Microwave Background ◽  
Background Spectrum ◽  
Black Hole Radiation ◽  
Black Hole Background ◽  
Theoretical Investigations

Current theoretical investigations seem to indicate the possibility of observing signatures of short distance physics in the cosmic microwave background spectrum. We try to gain a deeper understanding on why all information about this regime is lost in the case of black hole radiation but not necessarily so in a cosmological setting by using the moving mirror as a toy model for both backgrounds. The different responses of the Hawking and cosmic microwave background spectra to short distance physics are derived in the appropriate limit when the moving mirror mimics a black hole background or an expanding universe. The different sensitivities to new physics, displayed by both backgrounds, are clarified through an averaging prescription that accounts for the intrinsic uncertainty in their quantum fluctuations. We then proceed to interpret the physical significance of our findings for time-dependent backgrounds in the light of nonlocal string theory.

scholarly journals Signatures of short distance physics in the cosmic microwave background

2002 ◽  
Vol 66 (12) ◽  
Author(s):  
Nemanja Kaloper ◽  
Matthew Kleban ◽  
Albion Lawrence ◽  
Stephen Shenker
Keyword(s):  
Cosmic Microwave Background ◽  
Short Distance ◽  
Microwave Background

PROBE OF THE INTERACTION BETWEEN DARK SECTORS ON THE LARGE SCALE COSMIC MICROWAVE BACKGROUND ANISOTROPIES

2011 ◽  
Vol 20 (10) ◽  
pp. 2121-2124
Author(s):  
JIAN-HUA HE ◽  
BIN WANG
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Cosmic Microwave Background ◽  
Significant Influence ◽  
Large Scale ◽  
Power Spectra ◽  
Data Sets ◽  
Late Time ◽  
Microwave Background ◽  
Coincidence Problem

In this review, we study the signature of the interaction between dark energy (DE) and dark matter (DM) on the large-scale CMB anisotropies. We find the interaction has significant influence on the late time Integrated Sachs Wolfe effect (ISW). The positive coupling could suppress the low-l part of the power spectra. We also confront the interacting models with WMAP 5-year as well as other data sets. We find that these models are well-fitted and in 1σ range, the constrained coupling between dark sectors can solve the coincidence problem.

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