On chromonatural inflation in string theory

Abstract

Sourced gravitational waves in chromonatural inflation (CNI) can give rise to a chiral spectrum of tensor fluctuations that is considerably enhanced relative to the vacuum fluctuations. If the field content of CNI acts purely as a spectator (SCNI), the inflationary sector can be consistent with current data making SCNI very appealing in view of future observations. We investigate the prospects of embedding SCNI in string theory, in the framework of Kähler inflation in type IIB large volume string compactifications, with a spectator sector associated with gaugino condensation on multiply magnetised D7-branes. We first introduce a generalised field theory framework that describes non-trivial multifield inflation coupled to gauge fields of the form generically arising in supergravity and string theory. We then use these results to study numerically and analytically both the background evolution and the dynamics of cosmological perturbations. We show that a successful inflationary background evolution with a large enhancement of the gravitational wave spectrum and a controllable backreaction from the amplified tensor fluctuations can be achieved by considering suitable values of three parameters present in our scenario: the magnetic flux, the degree of the condensing gauge group and the wrapping number of the D7-brane. On the other hand, the required values for these quantities may present a challenge for its successful realisation within string theory. We also discuss these challenges and the model from the viewpoint of the weak gravity conjecture.

43 pages, 21 figures. References updated, typos corrected

References in corpus (16)

• Science with the space-based interferometer LISA. IV: Probing inflation with gravitational waves
• CMB-S4 Science Book, First Edition
• SPT-3G: A Next-Generation Cosmic Microwave Background Polarization Experiment on the South Pole Telescope
• Perturbations in generalized multi-field inflation
• Primordial Gravitational Waves from Axion-Gauge Fields Dynamics
• CLASS: The Cosmology Large Angular Scale Surveyor
• Non-Gaussianity from Instant and Tachyonic Preheating
• Aligned Natural Inflation in String Theory
• Gauge-flation trajectories in Chromo-Natural Inflation
• The rapid-turn inflationary attractor
• The Lyth Bound of Inflation with a Tilt
• Gravitational Waves and Scalar Perturbations from Spectator Fields
• Hyperinflation generalised: from its attractor mechanism to its tension with the `swampland conjectures'
• Can a spectator scalar field enhance inflationary tensor mode?
• On the viability of m**2 phi**2 and natural inflation
• Synthetic Gravitational Waves from a Rolling Axion Monodromy

Cited by in corpus (11)

• Cosmology with the Laser Interferometer Space Antenna
• The CosmoVerse White Paper: Addressing observational tensions in cosmology with systematics and fundamental physics
• New physics from the polarised light of the cosmic microwave background
• The Science of the Einstein Telescope
• Parity Violating Non-Gaussianity from Axion-Gauge Field Dynamics
• The Inflated Chern-Simons Number in Spectator Chromo-Natural Inflation
• Effective Field Theory of Chiral Gravitational Waves
• Hitchhiker's Guide to the Swampland: The Cosmologist's Handbook to the string-theoretical Swampland Programme
• Thermal effects on warm chromoinflation
• On the prospects of thermalization of axion-SU(2) inflation
• String loop origin for dark radiation and superheavy dark matter in type IIB compactifications