scholarly journals Cosmological perturbations inQCD¯-inflation: Estimates confronting the observations, including BICEP2

2014 ◽  
Vol 90 (4) ◽  
Author(s):  
Ariel R. Zhitnitsky
Keyword(s):  
Cosmological Perturbations

scholarly journals Cosmological perturbations in Gauss-Bonnet quasi-dilaton massive gravity

2021 ◽  
Vol 103 (12) ◽  
Author(s):  
Amin Rezaei Akbarieh ◽  
Sobhan Kazempour ◽  
Lijing Shao
Keyword(s):  
Massive Gravity ◽  
Cosmological Perturbations

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.

COSMOLOGICAL PERTURBATIONS: MYTHS AND FACTS

2004 ◽  
Vol 19 (13n16) ◽  
pp. 967-982 ◽  
Author(s):  
PAUL J. STEINHARDT
Keyword(s):  
Cosmological Perturbations ◽  
Cyclic Models

We discuss (and debunk) ten common myths about cosmological perturbations in inflationary and ekpyrotic/cyclic models and their implications for future observations.

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