# Curvature and isocurvature perturbations in two-field inflation

@article{Lalak2007CurvatureAI, title={Curvature and isocurvature perturbations in two-field inflation}, author={Zygmunt Lalak and David Langlois and Stefan Pokorski and Krzysztof Turzyński}, journal={Journal of Cosmology and Astroparticle Physics}, year={2007}, volume={2007}, pages={014 - 014} }

We study cosmological perturbations in two-field inflation, allowing for non-standard kinetic terms. We calculate analytically the spectra of curvature and isocurvature modes at Hubble crossing, up to first order in the slow-roll parameters. We also compute numerically the evolution of the curvature and isocurvature modes from well within the Hubble radius until the end of inflation. We show explicitly for a few examples, including the recently proposed model of ‘roulette’ inflation, how…

## 184 Citations

### Isocurvature perturbations during two-field inflation and reheating

- PhysicsGeneral Relativity and Gravitation
- 2019

We use Hamilton–Jacobi formalism to study the curvature and isocurvature perturbations during inflation. This formalism is suitable for going beyond slow roll regime. We solve the equation of fields’…

### Non-linear isocurvature perturbations and non-Gaussianities

- Physics
- 2008

We study non-linear primordial adiabatic and isocurvature perturbations and their non-Gaussianity. After giving a general formulation in the context of an extended δN formalism, we analyse in detail…

### Curvature Spectra and Nongaussianities in the Roulette Inflation Model

- Physics
- 2008

Using the gradient expansion method of Rigopoulos, Shellard and van Tent which treats cosmological perturbations as gradients on top of a homogeneous and isotropic FRW background, we study the…

### On cross-correlations between curvature and isocurvature perturbations during inflation

- Physics
- 2010

We investigate the effects of couplings between curvature and isocurvature perturbations before and around horizon-crossings during cosmological inflation. We consider a generalized two-field…

### On multifield inflation, adiabaticity and the speed of sound of the curvature perturbations

- Physics
- 2016

In this thesis we study some aspects of the very early Universe. We focus on the period of inflation, and show how the presence of many fields during this period can affect its low energy…

### Two-field warm inflation and its scalar perturbations on large scales

- Physics, Mathematics
- 2018

We explore the homogeneous background dynamics and the evolution of generated perturbations of cosmological inflation that is driven by multiple scalar fields interacting with a perfect fluid.Then we…

### Observational constraints on two-field warm inflation

- PhysicsPhysical Review D
- 2019

We study the two-field warm inflation models with a double quadratic potential and a linear temperature-dependent dissipative coefficient. We derive the evolution equation of all kinds of…

### Covariant evolution of perturbations during reheating in two-field inflation

- PhysicsJournal of Cosmology and Astroparticle Physics
- 2018

We develop a covariant method for studying the effects of a reheating phase on the primordial adiabatic and isocurvature perturbations in two-field models of inflation. To model the decay of the…

### On reaching the adiabatic limit in multi-field inflation

- Physics
- 2015

We calculate the scalar spectral index ns and the tensor-to-scalar ratio r in a class of recently proposed two-field no-scale inflationary models in supergravity. We show that, in order to obtain…

### Fermionic isocurvature perturbations

- Physics
- 2015

Isocurvature perturbations in the inflationary literature typically involve quantum fluctuations of bosonic field degrees of freedom. In this work, we consider isocurvature perturbations from…

## References

SHOWING 1-10 OF 39 REFERENCES

### Curvature and isocurvature perturbations from two-field inflation in a slow-roll expansion

- Physics
- 2006

We calculate the power spectra of primordial curvature and isocurvature perturbations from a general two-field inflation model at next-to-leading order correction in a slow-roll expansion. In…

### Slow-roll inflation for generalized two-field Lagrangians

- Physics
- 2005

We study the slow-roll regime of two-field inflation, in which the two scalar fields are also coupled through their kinetic terms. Such Lagrangians are motivated by particle physics and by…

### Correlated adiabatic and isocurvature perturbations from double inflation

- Physics
- 1999

It is shown that double inflation (two minimally coupled massive scalar fields) can produce correlated adiabatic and isocurvature primordial perturbations. Depending on the two relevant parameters of…

### Density perturbations from two field inflation

- Physics
- 1996

We discuss metric perturbations produced during a period of inflation in the early universe where two scalar fields evolve. The final scalar perturbation spectrum can be calculated in terms of the…

### Adiabatic and entropy perturbations from inflation

- Physics, Environmental Science
- 2000

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…

### Perturbations of extended inflation.

- PhysicsPhysical review. D, Particles and fields
- 1992

It is shown that in the particular case of old extended inflation, where the inflaton is trapped at a false-vacuum local minimum of its potential, its fluctuation does not contribute to the density perturbation, thus confirming earlier approximate calculations.

### Spectrum of curvature perturbations from hybrid inflation.

- PhysicsPhysical review. D, Particles and fields
- 1996

An exact expression for the amplitude of quantum fluctuations on all scales in the limit where the backreaction on the metric is neglected is given, a very good approximation for values of the inflaton field well below the Planck scale.

### Evolution of nonlinear cosmological perturbations.

- Physics, MathematicsPhysical review letters
- 2005

Full nonperturbative generalizations of the uniform density and comoving curvature perturbations are defined geometrically, independently of any coordinate system, and the equations governing their evolution on all scales are given.

### Spectral running and non-Gaussianity from slow-roll inflation in generalized two-field models

- Physics
- 2007

Theories beyond the standard model such as string theory motivate low energy effective field theories with several scalar fields which are not only coupled through a potential but also through their…