Starobinsky-Like Inflation in Dilaton-Brane Cosmology

Abstract

We discuss how Starobinsky-like inflation may emerge from dilaton dynamics in brane cosmology scenarios based on string theory, in which our universe is represented as a three-brane. The effective potential may acquire a constant term from a density of effectively point-like non-pertubative defects on the brane. Higher-genus corrections generate corrections to the effective potential that are exponentially damped at large field values, as in the Starobinsky model, but at a faster rate, leading to a smaller prediction for the tensor-to scalar perturbation ratio r. This may be compensated partially by logarithmic deformations on the world-sheet due to recoil of the defects due to scattering by string matter on the brane, which tend to enhance the tensor-to-scalar ratio.

6 pages, 1 figure, Note Added to discuss BICEP2 data in connection with the present class of stringy inflation models. References added. No effect on conclusions other than the statement that D-particle fluctuations may provide independent (from dilaton) sources of tensor perturbations that enhance the tensor-to-scalar ratio in agreement with BICEP2 data. Version to appear in Phys. Lett. B

References in corpus (2)

• Starobinsky-type Inflation in Dynamical Supergravity Breaking Scenarios
• Stringy Models of Modified Gravity: Space-time defects and Structure Formation

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