Abstract
We reconsider the predictions of inflation for the spectral index of scalar (energy density) fluctuations () and the tensor/scalar ratio () using a discrete, model-independent measure of the degree of fine-tuning required to obtain a given combination of (, ). We find that, except for cases with numerous unnecessary degrees of fine-tuning, is less than 0.98, measurably different from exact Harrison-Zel’dovich. Furthermore, if , in accord with current measurements, the tensor/scalar ratio satisfies , a range that should be detectable in proposed cosmic microwave background polarization experiments and direct gravitational wave searches.
- Received 28 August 2005
DOI:https://doi.org/10.1103/PhysRevLett.96.111301
©2006 American Physical Society