String Cosmology - Large-Field Inflation in String Theory

Abstract

This is a short review of string cosmology. We wish to connect string-scale physics as closely as possible to observables accessible to current or near-future experiments. Our possible best hope to do so is a description of inflation in string theory. The energy scale of inflation can be as high as that of Grand Unification (GUT). If this is the case, this is the closest we can possibly get in energy scales to string-scale physics. Hence, GUT-scale inflation may be our best candidate phenomenon to preserve traces of string-scale dynamics. Our chance to look for such traces is the primordial gravitational wave, or tensor mode signal produced during inflation. For GUT-scale inflation this is strong enough to be potentially visible as a B-mode polarization of the cosmic microwave background (CMB). Moreover, a GUT-scale inflation model has a trans-Planckian excursion of the inflaton scalar field during the observable amount of inflation. Such large-field models of inflation have a clear need for symmetry protection against quantum corrections. This makes them ideal candidates for a description in a candidate fundamental theory like string theory. At the same time the need of large-field inflation models for UV completion makes them particularly susceptible to preserve imprints of their string-scale dynamics in the inflationary observables, the spectral index $n_s$ and the fractional tensor mode power $r$. Hence, we will focus this review on axion monodromy inflation as a mechanism of large-field inflation in string theory.

34 pages, 1 figure, LaTeX, v2: typos fixed, 3 references added, agrees with published version in "Perspectives in String Phenomenology" and "International Journal of Modern Physics A"

References in corpus (20)

• BICEP2 I: Detection Of B-mode Polarization at Degree Angular Scales
• The Effective Field Theory of Inflation
• Flux Compactification
• A Natural Framework for Chaotic Inflation
• An Ignoble Approach to Large Field Inflation
• SUSY Breaking in Local String/F-Theory Models
• Systematics of String Loop Corrections in Type IIB Calabi-Yau Flux Compactifications
• Simple de Sitter Solutions
• Axion Inflation in Type II String Theory
• A Holographic Framework for Eternal Inflation
• Aligned Natural Inflation: Monodromies of two Axions
• An M theory Solution to the Hierarchy Problem
• Cosmological solutions of supercritical string theory
• Natural and Multi-Natural Inflation in Axion Landscape
• Natural Chaotic Inflation and UV Sensitivity
• Towards large r from [p,q]-inflation
• Big Bang Models in String Theory
• Combining Universal and Odd RR Axions for Aligned Natural Inflation
• A Short Review of Time Dependent Solutions and Space-like Singularities in String Theory
• D-brane Potentials in the Warped Resolved Conifold and Natural Inflation

Cited by in corpus (21)

• The Quest for B Modes from Inflationary Gravitational Waves
• Euclidean wormholes, baby universes, and their impact on particle physics and cosmology
• The Swampland Conjecture and F-term Axion Monodromy Inflation
• PBH dark matter from axion inflation
• Open string multi-branched and Kahler potentials
• Global Embedding of Fibre Inflation Models
• The Type IIA Flux Potential, 4-forms and Freed-Witten anomalies
• The Flux-Scaling Scenario: De Sitter Uplift and Axion Inflation
• Monodromy Dark Matter
• Trajectories with suppressed tensor-to-scalar ratio in Aligned Natural Inflation
• Towards Axion Monodromy Inflation with Warped KK-Modes
• D6-branes and axion monodromy inflation
• Flux Flattening in Axion Monodromy Inflation
• String Moduli Stabilization at the Conifold
• Effective models of inflation from a non-local framework
• DBI Galileon inflation in the light of Planck 2015
• New model of axion monodromy inflation and its cosmological implications
• Challenges for D-brane large-field inflation with stabilizer fields
• Explaining low l anomalies in the CMB power spectrum with resonant superstring excitations during inflation
• Inflation as an Information Bottleneck - A strategy for identifying universality classes and making robust predictions
• Hitchhiker's Guide to the Swampland: The Cosmologist's Handbook to the string-theoretical Swampland Programme