scholarly journals Cosmological perturbations in extended electromagnetism: General gauge invariant approach

2012 ◽  
Vol 85 (12) ◽  
Author(s):  
Roberto Dale ◽  
Diego Sáez
Keyword(s):  
Cosmological Perturbations ◽  
Gauge Invariant ◽  
Invariant Approach ◽  
General Gauge

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

Gauge-invariant approach and infrared behavior of the spinor propagator

1989 ◽  
Vol 78 (2) ◽  
pp. 185-191 ◽  
Author(s):  
A. N. Sisakyan ◽  
N. B. Skachkov ◽  
I. L. Solovtsov ◽  
O. Yu. Shevchenko
Keyword(s):  
Gauge Invariant ◽  
Infrared Behavior ◽  
Invariant Approach

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.

scholarly journals Hypersurface-invariant approach to cosmological perturbations

1995 ◽  
Vol 51 (2) ◽  
pp. 517-535 ◽  
Author(s):  
D. S. Salopek ◽  
J. M. Stewart
Keyword(s):  
Cosmological Perturbations ◽  
Invariant Approach
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