Michele Cicoli, Anshuman Maharana, F. Quevedo, C. P. Burgess
We consider a novel scenario for modulus stabilisation in IIB string compactifications in which the Kahler moduli are stabilised by a general set-up with two kinds of non-perturbative effects: (i) standard Kahler moduli-dependent non-perturbative effects from gaugino condensation on D7-branes or E3-instantons wrapping four-cycles in the geometric regime; (ii) dilaton-dependent non-perturbative effects from gaugino condensation on space-time filling D3-branes or E(-1)-instantons. For the LARGE Volume Scenario (LVS), the new dilaton-dependent non-perturbative effects provide a positive definite contribution to the scalar potential that can be arbitrarily tuned from fluxes to give rise to de Sitter vacua. Contrary to anti D3-branes at warped throats, this term arises from a manifestly supersymmetric effective action. We find two physically different realisations of this scenario in which the 'uplifting' term comes from F-terms of either blow-up modes or the dilaton. We discuss phenomenological and cosmological implications of this mechanism. This set-up also allows a realisation of the LVS for manifolds with zero or positive Euler number.
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http://arxiv.org/abs/1203.1750
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