Generating the curvature perturbation without an inflaton
Abstract
We present a mechanism for the origin of the largescale curvature perturbation in our Universe by the late decay of a massive scalar field, the curvaton. The curvaton is light during a period of cosmological inflation, when it acquires a perturbation with an almost scaleinvariant spectrum. This corresponds initially to an isocurvature density perturbation, which generates the curvature perturbation after inflation when the curvaton density becomes a significant fraction of the total. The isocurvature density perturbation disappears if the curvaton completely decays into thermalised radiation. Any residual isocurvature perturbation is 100% correlated with the curvature. The same mechanism can also generate the curvature perturbation in prebig bang/ekpyrotic models, provided that the curvaton has a suitable noncanonical kinetic term so as to generate a flat spectrum.
 Publication:

Physics Letters B
 Pub Date:
 January 2002
 DOI:
 10.1016/S03702693(01)013661
 arXiv:
 arXiv:hepph/0110002
 Bibcode:
 2002PhLB..524....5L
 Keywords:

 High Energy Physics  Phenomenology;
 Astrophysics;
 High Energy Physics  Theory
 EPrint:
 8 pages, minor corrections, reference added