Large N cosmology

@article{Brandenberger2004LargeNC,
  title={Large N cosmology},
  author={Robert H. Brandenberger and P. M. Ho and H. C. Kao},
  journal={Journal of Cosmology and Astroparticle Physics},
  year={2004},
  volume={2004},
  pages={011-011}
}
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… 
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