On: Natural Inflation

Abstract

We re-examine the original model of Natural inflation, in which the inflaton is a pseudo Nambu-Goldstone boson with potential of the form $V(\varphi )={\Lambda }^4[1\pm \cos (\varphi /f)]$, in light of recent data. We find that the model is alive and well. Successful inflation as well as recent data from the Wilkinson Microwave Anisotropy probe require $f>0.6m_{\mathrm{Pl}}$ (where $m_{\mathrm{Pl}}=1.22\times 10^{19}$ GeV) and $\Lambda \sim m_{GUT}$, scales which can be accommodated in particle physics models. The detectability of tensor modes from natural inflation in upcoming microwave background experiments is discussed. We find that natural inflation predicts a tensor/scalar ratio within reach of future observations.

Comments: 19 pages, 1 figure, in press, PRD