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  • Open Access

Smooth hybrid inflation in light of ACT DR6 data

Nobuchika Okada*

Osamu Seto†

  • *Contact author: okadan@ua.edu
  • †Contact author: seto@particle.sci.hokudai.ac.jp
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Phys. Rev. D 112, 083549 – Published 23 October, 2025

DOI: https://doi.org/10.1103/y9s8-7b5b

Abstract

Smooth hybrid inflation is a hybrid inflation model that is free from topological defects and predicts the density perturbation with the spectral index of about 0.97. We show that the prediction on the spectral index is robust regardless the power of nonrenormalizable terms and meets with the latest results reported by Atacama Cosmology Telescope. Viable scenarios for baryogenesis and dark matter are also discussed.

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Phys. Rev. D 112, 083549– Published 23 October, 2025
  • Received 25 June 2025
  • Accepted 30 September 2025
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