Adiabatic CMB perturbations in pre - big bang string cosmology

@article{Enqvist2002AdiabaticCP,
  title={Adiabatic CMB perturbations in pre - big bang string cosmology},
  author={Kari Enqvist and Martin S. Sloth},
  journal={Nuclear Physics},
  year={2002},
  volume={626},
  pages={395-409}
}
Abstract We consider the pre-Big-Bang scenario with a massive axion field which starts to dominate energy density when oscillating in an instanton-induced potential and subsequently reheats the universe as it decays into photons, thus creating adiabatic CMB perturbations. We find that the fluctuations in the axion field can give rise to a nearly flat spectrum of adiabatic perturbations with a spectral tilt Δn in the range −0.1≲ Δn ≲1. 

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References

SHOWING 1-10 OF 55 REFERENCES
Pre-big-bang in string cosmology
The duality-type symmetries of string cosmology naturally lead us to expect a pre-big-bang phase of accelerated evolution as the dual counterpart of the decelerating expansion era of standardExpand
Axion perturbation spectra in string cosmologies
Abstract We discuss the semi-classical perturbation spectra produced in the massless fields of the low energy string action in a pre big bang type scenario. Axion fields may possess an almostExpand
Dark matter axions in models of string cosmology
Abstract Axions are produced during a period of dilaton-driven inflation by amplification of quantum fluctuations. We show that for some range of string cosmology parameters and some range of axionExpand
Seeds of large-scale anisotropy in string cosmology
Pre-big-bang cosmology predicts tiny first-order dilaton and metric perturbations at very large scales. Here we discuss the possibility that other, more copiously generated, perturbations may act, atExpand
Cosmic microwave background anisotropies from pre-big bang cosmology
We present an alternative scenario for cosmic structure formation where initial fluctuations are due to Kalb-Ramond axions produced during a pre-big bang phase of inflation. We investigate whetherExpand
Cosmic microwave background anisotropies and extra dimensions in string cosmology
A recently proposed mechanism for large-scale structure in string cosmology—based on massless axionic seeds—is further analyzed and extended to the acoustic-peak region. Existence, structure, andExpand
Reheating and dangerous relics in pre-big-bang string cosmology
We discuss the mechanism of reheating in pre-big-bang string cosmology and we calculate the amount of moduli and gravitinos produced gravitationally and in scattering processes of the thermal bath.Expand
Constraints on pre-big bang models for seeding large-scale anisotropy by massive Kalb-Ramond axions
We discuss the conditions under which pre-big bang models can fit the observed large-scale anisotropy with a primordial spectrum of massive (Kalb– Ramond) axion fluctuations. The primordial spectrumExpand
What initial perturbations may be generated in inflationary cosmological models
Abstract Isothermal (isoinflaton) perturbations generated in cosmological models at the inflationary stage are discussed. The spectrum of such perturbations has been calculated for the example of aExpand
Particle production in string cosmology models
We compute spectra of particles produced during a dilaton-driven kinetic inflation phase within string cosmology models. The resulting spectra depend on the parameters of the model and on the type ofExpand
...
1
2
3
4
5
...