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arXiv · 2605.23827

Natural Metric-Affine Inflation: Reloaded

D. Kraiko·A. Racioppi
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Abstract

We revisit natural inflation within the framework of metric-affine gravity, considering the impact of a periodic non-minimal coupling between the inflaton and the Nieh-Yan term. Such a term, alone, leads to linear inflation predictions in the strong coupling limit and cannot help to rescue the natural inflation scenario. However, once an analogous non-minimal coupling with the Ricci scalar is added, agreement with data can be easily achieved. Remarkably, the scenario remains viable even with a sub-Planckian periodicity scale and relatively small (order of one) non-minimal couplings.

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D. Kraiko, A. Racioppi. 2026-05-22. Natural Metric-Affine Inflation: Reloaded. https://arxiv.org/abs/2605.23827

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