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arXiv · 2605.05317

Inflation and topology from the no-boundary state

Victor Godet
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Abstract

The no-boundary wavefunction for slow-roll inflation on the 3-sphere exponentially favors a small universe, in sharp disagreement with observations. We show that this problem is resolved by changing the spatial topology to the 3-torus. The sum over the ${\rm SL}(3,\mathbb{Z})$ family of geometries, computed using the theory of automorphic forms for ${\rm GL}(3)$, produces a wavefunction favoring a large inflating universe with ${\cal N} \gtrsim 250$ e-folds. We also compute corrections to the CMB power spectrum induced by torus moduli fluctuations.

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Victor Godet. 2026-05-06. Inflation and topology from the no-boundary state. https://arxiv.org/abs/2605.05317

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