scholarly journals Gauge invariant cosmological perturbations for the nonminimally coupled inflaton field

2010 ◽  
Vol 82 (12) ◽  
Author(s):  
Jan Weenink ◽  
Tomislav Prokopec
Keyword(s):  
Cosmological Perturbations ◽  
Gauge Invariant ◽  
Inflaton Field

scholarly journals Breaking the cosmological background degeneracy by two-fluid perturbations in f(R) gravity

2015 ◽  
Vol 24 (07) ◽  
pp. 1550053 ◽  
Author(s):  
Amare Abebe
Keyword(s):  
General Relativity ◽  
Exact Solutions ◽  
Structure Formation ◽  
Background Level ◽  
Cosmological Perturbations ◽  
Gauge Invariant ◽  
First Order ◽  
Cosmological Background ◽  
Theories Of Gravity ◽  
Two Fluid

One of the exact solutions of f(R) theories of gravity in the presence of different forms of matter exactly mimics the ΛCDM solution of general relativity (GR) at the background level. In this work we study the evolution of scalar cosmological perturbations in the covariant and gauge-invariant formalism and show that although the background in such a model is indistinguishable from the standard ΛCDM cosmology, this degeneracy is broken at the level of first-order perturbations. This is done by predicting different rates of structure formation in ΛCDM and the f(R) model both in the complete and quasi-static regimes.

Gauge-invariant cosmological perturbations

1980 ◽  
Vol 22 (8) ◽  
pp. 1882-1905 ◽  
Author(s):  
James M. Bardeen
Keyword(s):  
Cosmological Perturbations ◽  
Gauge Invariant

scholarly journals Cosmological perturbations: a new gauge-invariant approach

2001 ◽  
Vol 292 (3) ◽  
pp. 173-180 ◽  
Author(s):  
Sergei M. Kopeikin ◽  
Juan Ramirez ◽  
Bahram Mashhoon ◽  
Mikhail V. Sazhin
Keyword(s):  
Cosmological Perturbations ◽  
Gauge Invariant ◽  
Invariant Approach

scholarly journals On Gauge Invariant Cosmological Perturbations in UV-modified Hořava Gravity: A Brief Introduction

2018 ◽  
Vol 168 ◽  
pp. 08003 ◽  
Author(s):  
Mu-In Park
Keyword(s):  
Detailed Balance ◽  
Big Bang ◽  
Matter Field ◽  
Cosmological Perturbations ◽  
Scale Invariant ◽  
Gauge Invariant ◽  
Four Dimensions ◽  
Detailed Balance Condition ◽  
Scalar Matter ◽  
Horava Gravity

We revisit gauge invariant cosmological perturbations in UV-modified, z = 3 Hořava gravity with one scalar matter field, which has been proposed as a renormalizable gravity theory without the ghost problem in four dimensions. We confirm that there is no extra graviton modes and general relativity is recovered in IR, which achieves the consistency of the model. From the UV-modification terms which break the detailed balance condition in UV, we obtain scale-invariant power spectrums for non-inflationary backgrounds, like the power-law expansions, without knowing the details of early expansion history of Universe. This could provide a new framework for the Big Bang cosmology.

Local gauge-invariant cosmological perturbations

1992 ◽  
Vol 46 (8) ◽  
pp. 3360-3371 ◽  
Author(s):  
J. C. R. Magueijo
Keyword(s):  
Cosmological Perturbations ◽  
Gauge Invariant ◽  
Local Gauge

scholarly journals ASPECTS OF WARM-FLAT DIRECTIONS

2010 ◽  
Vol 25 (22) ◽  
pp. 4221-4237 ◽  
Author(s):  
TOMOHIRO MATSUDA
Keyword(s):  
Thermal Equilibrium ◽  
Strong Interactions ◽  
Cosmological Perturbations ◽  
Inflaton Field ◽  
Warm Inflation ◽  
Qualitative And Quantitative ◽  
Slow Roll ◽  
Dissipative Coefficient ◽  
Inflation Scenario

Considering the mechanism of dissipative slow-roll that has been used in warm inflation scenario, we show that dissipation may alter usual cosmological scenarios associated with SUSY-flat directions. We mainly consider SUSY-flat directions that have strong interactions with nonflat directions and may cause strong dissipation both in thermal and nonthermal backgrounds. An example is the Affleck–Dine mechanism in which dissipation may create significant (both qualitative and quantitative) discrepancies between the conventional scenario and the dissipative one. We also discuss several mechanisms of generating curvature perturbations in which the dissipative field, which is distinguished from the inflaton field, can be used as the source of cosmological perturbations. Considering the Morikawa–Sasaki dissipative coefficient, the damping caused by the dissipation may be significant for many MSSM flat directions even if the dissipation is far from thermal equilibrium.

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