Cosmological perturbation spectra from SL(4,R)-invariant effective actions
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.
Keywords
Cite
@article{arxiv.hep-th/0002215,
title = {Cosmological perturbation spectra from SL(4,R)-invariant effective actions},
author = {Helen A. Bridgman and David Wands},
journal= {arXiv preprint arXiv:hep-th/0002215},
year = {2009}
}
Comments
8 pages, 3 figures, revtex plus epsf, minor typos corrected, version to appear in Physical Review D