[1509.00024] Starobinsky-Type Inflation from $\alpha'$-Corrections

[1509.00024] Starobinsky-Type Inflation from $\alpha'$-Corrections: "Starobinsky-Type Inflation from α′-Corrections Benedict J. Broy, David Ciupke, Francisco G. Pedro, Alexander Westphal (Submitted on 31 Aug 2015) Working in the Large Volume Scenario (LVS) of IIB Calabi-Yau flux compactifications, we construct inflationary models from recently computed higher derivative (α′)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=V0(1−e−νϕ)2, where we obtain one set-up with ν=−1/3√ and one with ν=2/3√ corresponding to inflation occurring for increasing or decreasing ϕ 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≃(2…7)×10−3. They hence realise inflation with moderately large fields (Δϕ∼6MPl) 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. Comments: 29 pages, 6 figures Subjects: High Energy Physics - Theory (hep-th); Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc) Report number: IFT-UAM/CSIC-15-093, DESY-15-166 Cite as: arXiv:1509.00024 [hep-th]   (or arXiv:1509.00024v1 [hep-th] for this version)"

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