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arXiv · 2504.09218

Analogue of Chern-Simons invariant in non-metricity gravity and axion cosmology

Shin'ichi Nojiri·Sergei D. Odintsov
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Abstract

We propose a pseudo-scalar quantity, which is an analogue of the Chern-Simons invariant, in the framework of non-metricity gravity. By considering the coupling between the pseudo-scalar quantity and the axion, we give scenarios which may solve the problems of the axion misalignment, the $S_8$ problem, and the beginning of inflation. When the phase transition associated with the spontaneous breaking of the gauge symmetry of the electroweak theory or grand unified theories (GUTs) occurs, the pseudo-scalar quantity has a non-trivial value, which induces the misalignment of the axion field and axion particles are produced. If the gradient of the potential is small, the $S_8$ problem might be solved. We also propose a mechanism which induces inflation by the misalignment of the axion field generated by the phase transition of the GUTs.

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Shin'ichi Nojiri, Sergei D. Odintsov. 2025-04-12. Analogue of Chern-Simons invariant in non-metricity gravity and axion cosmology. https://arxiv.org/abs/2504.09218

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