Inflationary predictions for scalar and tensor fluctuations reconsidered

Latham A. Boyle, Paul J. Steinhardt, Neil Turok

Research output: Contribution to journalArticlepeer-review

82 Scopus citations


We reconsider the predictions of inflation for the spectral index of scalar (energy density) fluctuations (ns) and the tensor/scalar ratio (r) using a discrete, model-independent measure of the degree of fine-tuning required to obtain a given combination of (ns, r). We find that, except for cases with numerous unnecessary degrees of fine-tuning, ns is less than 0.98, measurably different from exact Harrison-Zel'dovich. Furthermore, if ns 0.95, in accord with current measurements, the tensor/scalar ratio satisfies r 10-2, a range that should be detectable in proposed cosmic microwave background polarization experiments and direct gravitational wave searches.

Original languageEnglish (US)
Article number111301
JournalPhysical review letters
Issue number11
StatePublished - 2006

All Science Journal Classification (ASJC) codes

  • General Physics and Astronomy


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