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  • Letter
  • Open Access

Independent connection in action during inflation

Alberto Salvio

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Phys. Rev. D 112, L061301 – Published 2 September, 2025

DOI: https://doi.org/10.1103/tq3v-vy3y

Abstract

The Atacama Cosmology Telescope (ACT) has recently released new measurements and constraints on inflationary observables. In this paper, it is shown that a component of a dynamical affine connection, which is independent of the metric, can easily drive inflation in agreement with these observations. Such geometrical explanation of inflation is analyzed in detail here in the minimal model, including the predictions for the scalar spectral index ns and its running αs, the amplitude of the scalar perturbations, and the tensor-to-scalar ratio r. Furthermore, this minimal model is shown to provide an inflationary attractor: arbitrary initial values of the kinetic energy density are dynamically attracted down to negligible values compared to the potential energy density in homogeneous and isotropic metrics. Also, the role of the Higgs boson during and after inflation is briefly discussed.

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Outline

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Phys. Rev. D 112, L061301– Published 2 September, 2025
  • Received 17 April 2025
  • Accepted 15 August 2025
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.

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