Independent connection in ACTion during inflation

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 analysed in detail here in the minimal model, including the predictions for the scalar spectral index $n_s$ and its running ${\alpha }_s$, 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.

v2: 6 pages, 4 figures, a plot and more explanations added, version accepted for publication in Physical Review D (Letter)

References in corpus (19)

• Planck 2018 results. X. Constraints on inflation
• DESI 2024 VI: Cosmological Constraints from the Measurements of Baryon Acoustic Oscillations
• BICEP / Keck XIII: Improved Constraints on Primordial Gravitational Waves using Planck, WMAP, and BICEP/Keck Observations through the 2018 Observing Season
• Barbero's Hamiltonian derived from a generalized Hilbert-Palatini action
• Real and complex connections for canonical gravity
• Quantum Gravity and Regge Calculus
• DESI 2024 III: Baryon Acoustic Oscillations from Galaxies and Quasars
• Classical and Quantum Initial Conditions for Higgs Inflation
• Higgs inflation with the Holst and the Nieh-Yan term
• Fractional attractors in light of the latest ACT observations
• Metric-Affine Gravity as an Effective Field Theory
• Inflation in Metric-Affine Quadratic Gravity
• Higgs inflation in Einstein-Cartan gravity
• Revisiting the Stability of Quadratic Poincaré Gauge Gravity
• Higgs-Modular Inflation
• Initial Conditions for Critical Higgs Inflation
• Inflating and Reheating the Universe with an Independent Affine Connection
• Einstein-Cartan pseudoscalaron inflation
• Natural Metric-Affine Inflation

Cited by in corpus (19)

• Keeping the relation between the Starobinsky model and no-scale supergravity ACTive
• Non-minimal coupling in light of ACT
• Increase of $n_s$ in regularized pole inflation & Einstein-Cartan gravity
• Improved Predictions on Higgs-Starobinsky Inflation and Reheating with ACT DR6 and Primordial Gravitational Waves
• $\alpha$-attractor inflation modified by GUP in light of ACT observations
• Inflation in $F(R)$ gravity models revisited after ACT
• Approximate reconstruction of inflationary potential with ACT observations
• Inflationary Models with Gauss-Bonnet Coupling in Light of ACT Observations
• Inflationary attractors and radiative corrections in light of ACT data
• Smooth hybrid inflation in light of ACT DR6 data
• Constraining non-minimally coupled squared-Quartic Hilltop Inflation in light of ACT observations
• Harrison-Zeldovich attractor: From Planck to ACT results
• Single-field D-type inflation in the minimal supergravity in light of Planck-ACT-SPT data
• Confronting Inflation and Reheating with Observations: Improved Predictions
• Twisting inflation to sub-Planckian axion decay constants
• Loop quantum inflation with inverse volume corrections in light of ACT data
• Inflationary assessment of $F(\mathcal{R},\tilde{\mathcal{R}})$ Einstein-Cartan models
• Reheating in geometric Weyl-invariant Einstein-Cartan gravity
• Constraints on non-canonical chaotic inflation from ACT DR6 and BICEP/Keck data