Large N cosmology
Abstract
We motivate inflationary scenarios with many scalar fields, and give a complete formulation of adiabatic and entropy perturbations. We find that if the potential is very flat, or if the theory has a SO(N) symmetry, the calculation of the fluctuation spectrum can be carried out in terms of merely two variables without any further assumption. We do not have to assume slow roll or SO(N) invariance for the background fields. We give some examples to show that, even if the slow roll assumption holds, the spectrum of fluctuations can be quite different from the case when there is a single inflaton.
 Publication:

Journal of Cosmology and Astroparticle Physics
 Pub Date:
 November 2004
 DOI:
 10.1088/14757516/2004/11/011
 arXiv:
 arXiv:hepth/0312288
 Bibcode:
 2004JCAP...11..011B
 Keywords:

 High Energy Physics  Theory;
 Astrophysics;
 General Relativity and Quantum Cosmology;
 High Energy Physics  Phenomenology
 EPrint:
 LaTex file, 22 pages, references added