Delta N Formalism in Cosmological Perturbation Theory

10.1142/10953 ◽  
2018 ◽  
Author(s):  
Ali Akbar Abolhasani ◽  
Hassan Firouzjahi ◽  
Atsushi Naruko ◽  
Misao Sasaki
Keyword(s):  
Perturbation Theory ◽  
Cosmological Perturbation ◽  
Cosmological Perturbation Theory

COSMOLOGICAL PERTURBATIONS IN GENERALIZED GRAVITY THEORIES

2004 ◽  
Vol 19 (13n16) ◽  
pp. 1203-1206 ◽  
Author(s):  
HYERIM NOH ◽  
JAI-CHAN HWANG
Keyword(s):  
Perturbation Theory ◽  
Cosmological Perturbations ◽  
Cosmological Perturbation ◽  
Cosmological Perturbation Theory ◽  
String Correction ◽  
Gravity Theories ◽  
Correction Terms ◽  
Classical Evolution

We present cosmological perturbation theory based on generalized gravity theories including string correction terms as well as a tachyonic complication. The classical evolution as well as the quantum generation processes in these variety of gravity theories are presented in unified forms. These apply both to the scalar- and tensor-type perturbations.

scholarly journals Induced gravitational waves in a general cosmological background

2020 ◽  
Vol 29 (03) ◽  
pp. 2050028 ◽  
Author(s):  
Guillem Domènech
Keyword(s):  
Black Hole ◽  
Perturbation Theory ◽  
Equation Of State ◽  
Gravitational Waves ◽  
Primordial Black Hole ◽  
Cosmological Perturbation ◽  
Cosmological Perturbation Theory ◽  
Cosmological Background ◽  
Integral Formulas ◽  
Small Scales

Gravitational waves (GWs) are inevitably produced by second-order terms in cosmological perturbation theory. Most notably, the so-called induced (GWs) are a window to the small scales part of the primordial spectrum of fluctuations and a key counterpart to the primordial black hole (PBH) scenario. However, semi-analytical solutions are only known for matter and radiation domination eras. In this paper, we present new analytic integral formulas for the induced GWs on subhorizon scales in a general cosmological background with a constant equation-of-state. We also discuss applications to a peaked primordial scalar power spectrum and the PBH scenario.

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