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arXiv · hep-th/0002215

Cosmological perturbation spectra from SL(4,R)-invariant effective actions

Helen A. Bridgman·David Wands
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Abstract

We investigate four-dimensional cosmological vacuum solutions derived from an effective action invariant under global SL(n,R) transformations. We find the general solutions for linear axion field perturbations about homogeneous dilaton-moduli-vacuum solutions for an SL(4,R)-invariant action and find the spectrum of super-horizon perturbations resulting from vacuum fluctuations in a pre big bang scenario. We show that for SL(n,R)-invariant actions with n>3 there exists a regime of parameter space of non-zero measure where all the axion field spectra have positive spectral tilt, as required if light axion fields are to provide a seed for anisotropies in the microwave background and large-scale structure in the universe.

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Helen A. Bridgman, David Wands. 2000-04-13. Cosmological perturbation spectra from SL(4,R)-invariant effective actions. https://doi.org/10.1103/physrevd.61.123514

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