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Inflation versus Cyclic Predictions for Spectral Tilt

Justin Khoury·Paul J. Steinhardt·Neil Turok
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Abstract

We present a simple, nearly model-independent estimate that yields the predictions of the simplest inflationary and ekpyrotic/cyclic models for the spectral tilt of the primordial density inhomogeneities. Remarkably, we find that the simplest models yield an identical result: n_s is approximately 0.95. For inflation, the same estimate predicts a ratio of tensor to scalar contributions to the low multipoles of the microwave background anisotropy of T/S=20%; the tensor contribution is negligible for ekpyrotic/cyclic models.

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Justin Khoury, Paul J. Steinhardt, Neil Turok. 2003-09-06. Inflation versus Cyclic Predictions for Spectral Tilt. https://doi.org/10.1103/physrevlett.91.161301

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