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