Starobinsky-Type Inflation from $\alpha'$-Corrections

Broy, Benedict; Pedro, Francisco G.; Ciupke, David; Westphal, Alexander

Preprint/Report

PUBDB-2015-03906

Starobinsky-Type Inflation from $\alpha'$-Corrections

Broy, B. (Corresponding author)DESY* ; Ciupke, D.DESY* ; Pedro, F. G. ; Westphal, A.DESY*

2015

This record in other databases:

Report No.: DESY-15-166; IFT-UAM/CSIC-15-093

Abstract: Working in the Large Volume Scenario (LVS) of IIB Calabi-Yau flux compactifications, we construct inflationary models from recently computed higher derivative $(\alpha')^3$-corrections. Inflation is driven by a Kaehler modulus whose potential arises from the aforementioned corrections, while we use the inclusion of string loop effects just to ensure the existence of a graceful exit when necessary. The effective inflaton potential takes a Starobinsky-type form $V=V_0(1-e^{-\nu\phi})^2$, where we obtain one set-up with $\nu=-1/\sqrt{3}$ and one with $\nu=2/\sqrt{3}$ corresponding to inflation occurring for increasing or decreasing $\phi$ respectively. The inflationary observables are thus in perfect agreement with PLANCK, while the two scenarios remain observationally distinguishable via slightly varying predictions for the tensor-to-scalar ratio $r$. Both set-ups yield $r\simeq (2\ldots 7)\,\times 10^{-3}$. They hence realise inflation with moderately large fields $\left(\Delta\phi\sim 6\thinspace M_{Pl}\right)$ without saturating the Lyth bound. Control over higher corrections relies in part on tuning underlying microscopic parameters, and in part on intrinsic suppressions. The intrinsic part of control arises as a leftover from an approximate effective shift symmetry at parametrically large volume.

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