Swampland Conjectures through ACT Observations: Observational Signatures of Radiative-Corrected Inflation

Abstract

We investigate the consistency of radiatively corrected inflationary models with both the latest observational data from the Atacama Cosmology Telescope (ACT) combined with Planck 2018 and Baryon Acoustic Oscillation (BAO) measurements, and the theoretical constraints imposed by the swampland program. We systematically test two distinct models against three key swampland conjectures: the further refined de Sitter swampland conjecture (FRDSSC), the scalar weak gravity conjecture (SWGC), and the strong scalar weak gravity conjecture (SSWGC). Model I, based on radiatively corrected Higgs inflation, satisfies the FRDSSC and remains consistent with current observational constraints ($n_s = 0.9743 \pm 0.0034$, $r < 0.038$), but fails to meet the SWGC and SSWGC requirements, indicating limited theoretical compatibility with quantum gravity principles. In contrast, Model II, incorporating radiative corrections with scalar sectors, demonstrates full consistency by satisfying all three swampland conjectures simultaneously while maintaining observational viability. The compatibility of Model II is highly sensitive to the non-minimal coupling $\xi$ and renormalization scales $\mu_b$, with larger values extending the range of swampland-consistent solutions. Our results highlight the critical role of radiative corrections in achieving simultaneous theoretical and observational consistency, and identify Model II as a promising candidate for a fully viable inflationary scenario within the swampland framework. This work provides a methodology for classifying inflationary models based on their swampland compatibility, demonstrating that satisfaction of the FRDSSC alone is insufficient for full theoretical consistency.