Dynamical selection of the primordial density fluctuation amplitude

Jean Luc Lehners, Paul J. Steinhardt

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


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.

Original languageEnglish (US)
Article number081301
JournalPhysical review letters
Issue number8
StatePublished - Feb 24 2011

All Science Journal Classification (ASJC) codes

  • General Physics and Astronomy


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