Inflation with multiple sound speeds: A model of multiple DBI type actions and non-Gaussianities

@article{Cai2009InflationWM,
  title={Inflation with multiple sound speeds: A model of multiple DBI type actions and non-Gaussianities},
  author={Yi Cai and Haijuan Xia},
  journal={Physics Letters B},
  year={2009},
  volume={677},
  pages={226-234}
}

Figures from this paper

Local non-Gaussianity from rapidly varying sound speeds

We study the effect of non-trivial sound speeds on local-type non-Gaussianity during multiple-field inflation. To this end, we consider a multiple-DBI model and use the δN formalism to track the

Local non-Gaussianity from rapidly varying sound speeds

We study the effect of non-trivial sound speeds on local-type non-Gaussianity during multiple-field inflation. To this end, we consider a multiple-DBI model and use the δN formalism to track the

Preheating in a DBI Inflation Model

We study the preheating process in a model of DBI inflation with a DBI-type inflaton coupling to a canonical entropy field. At the end of inflation, the inflaton field oscillates around its vacuum

Non-Gaussianity in multi-sound-speed disformally coupled inflation

Most, if not all, scalar-tensor theories are equivalent to General Relativity with a disformally coupled matter sector. In extra-dimensional theories such a coupling can be understood as a result of

Inhomogeneous reheating scenario with DBI fields

We discuss a new mechanism which can be responsible for the origin of the primordial perturbation in inflationary models, the inhomogeneous DBI reheating scenario. Light DBI fields fluctuate during

Covariant second-order perturbations in generalized two-field inflation

It is demonstrated that kinetic-term derivatives and covariant field derivatives do commute in a proper covariant framework, which was not realized before in the literature, and a set of generalized slow-roll parameters is defined, using a unified notation.

Combined local and equilateral non-Gaussianities from multifield DBI inflation

We study multifield aspects of Dirac-Born-Infeld (DBI) inflation. More specifically, we consider an inflationary phase driven by the radial motion of a D-brane in a conical throat and determine how

Primordial fluctuations and non-Gaussianities from multifield DBI Galileon inflation

We study a cosmological scenario in which the DBI action governing the motion of a D3-brane in a higher-dimensional spacetime is supplemented with an induced gravity term. The latter reduces to the

Primordial perturbations from string inflation

In this work we explore the correspondence between the physical processes associated with inflationary models inspired by string theory and the subsequent non-Gaussian signatures imprinted in the
...

References

SHOWING 1-10 OF 91 REFERENCES

Primordial perturbations and non-Gaussianities in DBI and general multifield inflation

We study cosmological perturbations in general inflation models with multiple scalar fields and arbitrary kinetic terms, with special emphasis on the multifield extension of Dirac-Born-Infeld (DBI)

Perturbations in generalized multi-field inflation

We study the linear perturbations of multi-field inflationary models governed by a Lagrangian which is a general function of the scalar fields and of a global kinetic term combining their spacetime

Large non-Gaussianities in single-field inflation

While adding features to a potential can improve the fit to the two-point function, these are generically associated with a greatly enhanced signal at the three-point level, which may lead to a consistency check on models of inflation with non-smooth potentials.

Primordial fluctuations and non-Gaussianities in multifield Dirac-Born-Infeld inflation.

It is shown that the adiabatic and entropy modes propagate with a common effective sound speed and are thus amplified at the sound horizon crossing and this could strongly affect the observable curvature power spectrum as well as the amplitude of non-Gaussianities, although their shape remains as in the single-field Dirac-Born-Infeld case.

Generation and characterization of large non-Gaussianities in single field inflation

Two distinct mechanisms by which a non-trivial potential can generate large non-Gaussianities are discussed, and a significantly improved approach to regularizing and numerically evaluating the integrals that contribute to the three-point function is presented.

Near scale invariance with modified dispersion relations

We describe a novel mechanism for generating a nearly scale invariant spectrum of adiabatic perturbations during a non-inflationary stage. It relies on a modified dispersion relation that contains

The shape of non-Gaussianities

We study the dependence on the configuration in momentum space of the primordial three-point function of density perturbations in several different scenarios: standard slow-roll inflation, curvaton

Dynamics of Assisted Inflation

We investigate the dynamics of the recently proposed model of assisted inflation. In this model an arbitrary number of scalar fields with exponential potentials evolve towards an inflationary scaling

Non-Gaussianities from ekpyrotic collapse with multiple fields

We compute the non-Gaussianity of the curvature perturbation generated by ekpyrotic collapse with multiple fields. The transition from the multi-field scaling solution to a single-field dominated

Adiabatic and entropy perturbations from inflation

We study adiabatic ~curvature! and entropy ~isocurvature! perturbations produced during a period of cosmological inflation that is driven by multiple scalar fields with an arbitrary interaction
...