Primordial Non-Gaussianity and Gravitational Waves: Observational Tests of Brane Inflation in String Theory

Abstract

We study brane inflation scenarios in a warped throat geometry and show that there exists a consistency condition between the non-Gaussianity of the curvature perturbation and the amplitude and scale-dependence of the primordial gravitational waves. This condition is independent of the warping of the throat and the form of the inflaton potential. We find that such a relation could be tested by a future CMB polarization experiment if the Planck satellite is able to detect both a gravitational wave background and a non-Gaussian statistic. In models where the observable stage of inflation occurs when the brane is in the tip region of the throat, we derive a further consistency condition involving the scalar spectral index, the tensor-scalar ratio and the curvature perturbation bispectrum. We show that when such a relation is combined with the WMAP3 results, it leads to a model-independent bound on the gravitational wave amplitude given by 0.001 < r < 0.01. This corresponds to the range of sensitivity of the next generation of CMB polarization experiments.

7 pages, uses RevTeX4. v2, replaced with version accepted by Phys. Rev. D

References in corpus (3)

• Prospects for direct detection of primordial gravitational waves
• DBI Inflation in the Tip Region of a Warped Throat
• Heating in Brane Inflation and Hidden Dark Matter

Cited by in corpus (28)

• Galileon inflation
• Primordial perturbations and non-Gaussianities in DBI and general multi-field inflation
• A Microscopic Limit on Gravitational Waves from D-brane Inflation
• Primordial fluctuations and non-Gaussianities in multi-field DBI inflation
• Route to nonlocal cosmology
• Phenomenology of D-Brane Inflation with General Speed of Sound
• Comparing Infrared Dirac-Born-Infeld Brane Inflation to Observations
• Nongaussianity from Tachyonic Preheating in Hybrid Inflation
• Riding on irrelevant operators
• Large Nongaussianity from Nonlocal Inflation
• Gravitational Wave Constraints on DBI Inflation
• On the full quantum trispectrum in multi-field DBI inflation
• Lorentz boost and non-Gaussianity in multi-field DBI-inflation
• On Power Law Inflation in DBI Models
• Primordial Non-Gaussianities from the Trispectra in Multiple Field Inflationary Models
• A Consistency Relation for Power Law Inflation in DBI models
• IR Inflation from Multiple Branes
• Constraints on Brane Inflation and Cosmic Strings
• DBI N-flation
• Gravitational Wave Constraints on Multi-Brane Inflation
• Warped Wilson Line DBI Inflation
• Bridging geometries and potentials in DBI cosmologies
• Enhanced Inflation in the Dirac-Born-Infeld framework
• Inflation in DBI models with constant gamma
• Reconstructing Single Field Inflationary Actions From CMBR Data
• Bounds on Tensor wave and Twisted Inflation
• The string theory swampland in the Euclid, SKA and Vera Rubin observatory era
• On the four-dimensional effective theories in brane-worlds