# Horizon-preserving dualities and perturbations in non-canonical scalar field cosmologies

@article{Geshnizjani2011HorizonpreservingDA, title={Horizon-preserving dualities and perturbations in non-canonical scalar field cosmologies}, author={Ghazal Geshnizjani and William H. Kinney and Azadeh Moradinezhad Dizgah}, journal={Journal of Cosmology and Astroparticle Physics}, year={2011}, volume={2012}, pages={015-015} }

We generalize the cosmological duality between inflation and cyclic contraction under the interchange a↔H to the case of non-canonical scalar field theories with varying speed of sound. The single duality in the canonical case generalizes to a family of three dualities constructed to leave the cosmological acoustic horizon invariant. We find three classes of models: (I) DBI inflation, (II) the non-canonical generalization of cyclic contraction, and (III) a new cosmological solution with rapidly…

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## References

SHOWING 1-10 OF 54 REFERENCES

### Observational signatures of gravitational couplings in DBI inflation

- Physics
- 2010

In scalar-tensor theories the scalar fields generically couple nontrivially to gravity. We study the observable properties of inflationary models with nonminimally coupled inflaton and…

### Duality invariance of cosmological perturbation spectra

- Physics
- 1999

I show that cosmological perturbation spectra produced from quantum fluctuations in massless or self-interacting scalar fields during an inflationary era remain invariant under a two parameter family…

### Flow in cyclic cosmology

- Physics
- 2010

In this paper, we use a known duality between expanding and contracting cosmologies to construct a dual of the inflationary flow hierarchy applicable to contracting cosmologies such as ekpyrotic and…

### Triality between inflation, cyclic and phantom cosmologies

- Physics
- 2004

It is shown that any spatially flat and isotropic universe undergoing accelerated expansion driven by a self-interacting scalar field can be directly related to a contracting, decelerating cosmology.…

### Towards a Cosmological Dual to Inflation

- Physics
- 2011

We derive all single-field cosmologies with unit sound speed that generate scale invariant curvature perturbations on a dynamical attractor background. We identify three distinct phases: slow-roll…

### Quantum modes in DBI inflation: Exact solutions and constraints from vacuum selection

- Physics
- 2008

We study a two-parameter family of exactly solvable inflation models with variable sound speed, and derive a corresponding exact expression for the spectrum of curvature perturbations. We generalize…

### Strong coupling problem with time-varying sound speed

- Physics
- 2011

For a single scalar field with unit sound speed minimally coupled to Einstein gravity, there are exactly three distinct cosmological solutions which produce a scale invariant spectrum of curvature…

### Near scale invariance with modified dispersion relations

- Physics
- 2006

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…

### Inflation: Flow, fixed points and observables to arbitrary order in slow roll

- Physics
- 2002

I generalize the inflationary flow equations of Hoffman and Turner to arbitrary order in slow roll. This makes it possible to study the predictions of slow roll inflation in the full observable…