2024/10/08 by Mariaveronica De Angelis, De Angelis, Mariaveronica, Chiara Cecchini +3
Physics and Astronomy · #Astronomy and Astrophysical Research #Cosmology and Gravitation Theories #Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences #High Energy Physics - Theory (hep-th) #Scientific Research and Discoveries
paper · pdf · doi:10.48550/arxiv.2410.05977
openalex publication_date 2024/10/08 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
This paper investigates a scale-invariant inflationary model characterized by a scalar field non-minimally coupled to gravity and a curvature term quadratic in the Ricci scalar. The model's dynamic is analyzed using a full numerical solution of the two-field system, going beyond previous analytical studies. We derive robust constraints on the model parameters using the latest Cosmic Microwave Background (CMB) data from Planck and BICEP/Keck. The study confirms that scale-invariance effectively reduces the system to single-field dynamics, eliminating entropy perturbations and ensuring stability. Key predictions include a minimal level of primordial gravitational waves with a tensor-to-scalar ratio r > 0.003, which upcoming CMB experiments are well-positioned to test. The model is compared to Starobinsky and α - attractor inflation, with future observations of tensor modes offering a potential discriminator between them. Overall, the results suggest that scale-invariant inflation is a viable and competitive framework for explaining early universe dynamics and predicting cosmological observables.