Dynamical Selection of the Primordial Density Fluctuation Amplitude
arXiv:1008.4567 · doi:10.1103/PhysRevLett.106.081301
Abstract
In inflationary models, the predicted amplitude of primordial density perturbations Q is much larger than the observed value (~10^{-5}) for natural choices of parameters. To explain the requisite exponential fine-tuning, anthropic selection is often invoked, especially in cases where microphysics is expected to produce a complex energy landscape. By contrast, we find examples of ekpyrotic models based on heterotic M-theory for which dynamical selection naturally favors the observed value of Q.
4 pages; v2: version to be published in PRL
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