Ultraviolet Completion of the Big Bang in Quadratic Gravity

Abstract

We present a quantum quadratic gravity inflationary scenario that can accommodate the new cosmological constraints, which have disfavored Starobinsky inflation. The theory is asymptotically free in the ultraviolet, but 1-loop running is found to dynamically lead to slow-roll inflation toward the infrared. When a large number of matter fields contribute to the beta functions, the spectral index and the tensor-to-scalar ratio can be phenomenologically viable. We find that as inflation ends, the theory approaches its strong coupling regime and general relativity must emerge, as an effective field theory, as the universe must reheat and enter its standard radiation era. In order to avoid strong coupling, a minimum tensor-to-scalar ratio of 0.01 is predicted for this theory. Our framework offers a laboratory for connecting a concrete ultraviolet completion (quantum quadratic gravity) with inflationary dynamics, reheating, and precise cosmological observations.

6 pages + 7-page appendix, 6 figures; v2: minor additions and references added, matches PRL published version

References in corpus (21)

• 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
• Dark energy in modified Gauss-Bonnet gravity: late-time acceleration and the hierarchy problem
• No-ghost theorem for the fourth-order derivative Pais-Uhlenbeck oscillator model
• Fixed Points of Higher Derivative Gravity
• Solution to the ghost problem in fourth order derivative theories
• From Planck data to Planck era: Observational tests of Holographic Cosmology
• The Ostrogradsky instability can be overcome by quantum physics
• Predictions of quantum gravity in inflationary cosmology: effects of the Weyl-squared term
• Inflation with a Weyl term, or ghosts at work
• A non-Perturbative and Background-Independent Formulation of Quadratic Gravity
• On the Ghost Problem of Conformal Gravity
• Running couplings and unitarity in a 4-derivative scalar field theory
• Starobinsky inflation with a quadratic Weyl tensor
• Making sense of ghosts
• When tadpoles matter: One-loop corrections for spectator Higgs in inflation
• UV-complete 4-derivative scalar field theory
• Precision predictions of Starobinsky inflation with self-consistent Weyl-squared corrections
• Conformal Cores of Quantum Black Holes in Quadratic Gravity
• Primordial Gravitational Waves in Quadratic Gravity
• Strict renormalizability as a paradigm for fundamental physics