Inflationary potentials in DBI models

Abstract

We study DBI inflation based upon a general model characterized by a power-law flow parameter $\epsilon (\varphi )\propto {\varphi }^{\alpha }$ and speed of sound $c_s(\varphi )\propto {\varphi }^{\beta }$, where $\alpha$ and $\beta$ are constants. We show that in the slow-roll limit this general model gives rise to distinct inflationary classes according to the relation between $\alpha$ and $\beta$ and to the time evolution of the inflaton field, each one corresponding to a specific potential; in particular, we find that the well-known canonical polynomial (large- and small-field), hybrid and exponential potentials also arise in this non-canonical model. We find that these non-canonical classes have the same physical features as their canonical analogs, except for the fact that the inflaton field evolves with varying speed of sound; also, we show that a broad class of canonical and D-brane inflation models are particular cases of this general non-canonical model. Next, we compare the predictions of large-field polynomial models with the current observational data, showing that models with low speed of sound have red-tilted scalar spectrum with low tensor-to-scalar ratio, in good agreement with the observed values. These models also show a correlation between large non-gaussianity with low tensor amplitudes, which is a distinct signature of DBI inflation with large-field polynomial potentials.

Minor changes, reference added. Version submitted to JCAP

References in corpus (27)

• Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Interpretation
• k-Inflation
• Supergravity and a Confining Gauge Theory: Duality Cascades and $\chi$SB-Resolution of Naked Singularities
• Hybrid Inflation
• Towards Inflation in String Theory
• Perturbations in k-inflation
• DBI in the Sky
• Observational Signatures and Non-Gaussianities of General Single Field Inflation
• Scalar Speed Limits and Cosmology: Acceleration from D-cceleration
• String Cosmology: A Review
• Effects of Scale-Dependent Non-Gaussianity on Cosmological Structures
• Racetrack Inflation
• Inflation: flow, fixed points and observables to arbitrary order in slow roll
• Cosmic microwave background measurements can discriminate among inflation models
• Roulette Inflation with Kähler Moduli and their Axions
• Observing Brane Inflation
• Phenomenology of D-Brane Inflation with General Speed of Sound
• Comparing Infrared Dirac-Born-Infeld Brane Inflation to Observations
• Quantum modes in DBI inflation: exact solutions and constraints from vacuum selection
• Inflation at Low Scales: General Analysis and a Detailed Model
• Latest inflation model constraints from cosmic microwave background measurements
• A Consistency Relation for Power Law Inflation in DBI models
• Non-canonical generalizations of slow-roll inflation models
• On the Slow Roll Expansion for Brane Inflation
• Tensors, non-Gaussianities, and the future of potential reconstruction
• Bridging geometries and potentials in DBI cosmologies
• Inflation in DBI models with constant gamma

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