title: Horizon ratio bound for inflationary fluctuations.
abstract: We demonstrate that the gravity wave background amplitude implies a robust upper bound on the wavelength-to-horizon ratio at the end of inflation: lambda/H(-1) less than or approximately equal e(60), as long as the cosmic energy density does not drop faster than radiation subsequent to inflation. This limit implies that N, the number of e-folds between horizon exit and the end of inflation for wave modes of interest, is less, similar 60 plus a model-dependent factor-for vast classes of slow-roll models, N less than or approximately equal 67. As an example, this bound solidifies the tension between observations of the cosmic microwave background anisotropies and chaotic inflation with a phi(4) potential by closing the escape hatch of large N (<62).
authors.affiliation: NASA/Fermilab Astrophysics Center, Fermi National Accelerator Laboratory, Batavia, Illinois 60510, USA.
authors.forename: Scott
authors.initials: S
authors.lastname: Dodelson
authors.forename: Lam
authors.initials: L
authors.lastname: Hui