Curvature and isocurvature

perturbations in two-field inflation

Krzysztof Turzyński(University of Michigan)

based on arXiv:0704.0212 with Z.Lalak, D.Langlois and S.Pokorski

Inflation

V

• solves the flatness problem

• solves the horizon problem

• dilutes any preexisting relics

• generates primordial density perturbations through quantum fluctuations of the coupled inflaton-gravity system

V2

2

1 V 2

2

1 Vp 2

2

1

22

2

2 PlMH

23H

V

small = slow-roll

03 VH

23

1

PlMa

aH

Curvature perturbations

Q gauge invariant variable describing perturbations

Q

HR 3-dim curvature of the comoving density

hypersurfaces

Evolution of perturbations

Road map

inflation radiation domination

matter domination

dark energy domination

CMB

hic sunt

leones

horizon length scale

Observations and inflation

10–4 10–3

10–2

10–1

10–3

10–2

Ellis, Lalak, Pokorski, kt, 2006

Motivation for multi-field scenarios

V

inflat

ion

SUSY breaking

Curvature and isocurvature perturbations

Hubble crossing

inflation ends

bev ,

fixed k

curvatureperturbation

isocurvatureperturbation

Equations

Examples

doubleinflation

rouletteinflation

Examples

rouletteinflation

Examples

Conclusions

good motivation to look for the implications of next-to-minimal models of inflation

richer dynamics; possible generation of isocurvature perturbations (after reheating)

message of caution: predictions may differ from the single-field case

We have a tool (for studying the evolution of the multi-inflaton systems)

and won’t hesitate to use it!