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Authors: Wessel Valkenburg, Lawrence M. Krauss, Jan Hamann

Date: 22 Apr 2008

Abstract: In this work we explore the effect of choosing flat priors on different parameterizations on the estimation of the tensor-to-scalar ratio and other parameters describing inflation. We show that a flat prior on the scale of inflation does not correspond to a flat prior on the tensor-to-scalar ratio, and that current data is not strong enough to render parameter estimation parameterization independent. Most importantly, we show that a flat prior on the scale of inflation raises the predicted tensor contribution, leading to a mild, yet non-zero 68 % c.l. lower bound on tensor perturbations from existing data. Which prior to choose remains for the moment a matter of taste. However this work provides more reason for optimism with respect to the possibility of future detection of primordial gravitational waves.

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