The lessons from the running of the tensor-to-scalar ratio

Abstract

We derive a simple consistency relation from the running of the tensor-to-scalar ratio. This new relation is first order in the slow-roll approximation. While for single field models we can obtain what can be found by using other observables, multi-field cases in general give non-trivial contributions dependent on the geometry of the field space and the inflationary dynamics, which can be probed observationally from this relation. The running of the tensor-to-scalar ratio may be detected by direct laser interferometer experiments.

arXiv comment(v1) 7 pages, 1 figure; (v2) Discussions refined and references added; (v3) More discussions on detectability, to appear in Physical Review D

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• Generalized Uncertainty Principle: Approaches and Applications
• Blue Tensor Spectrum from Particle Production during Inflation
• Non-Bunch-Davies Initial State Reconciles Chaotic Models with BICEP and Planck
• Effects of quantum gravity on the inflationary parameters and thermodynamics of the early universe
• Blue running of the primordial tensor spectrum
• Cosmological observables in multi-field inflation with a non-flat field space
• Minimal-supersymmetric extended inflation field in Horava-Lifshitz gravity
• What we can learn from the spectral index of the tensor mode
• Minimal gauge inflation