https://doi.org/10.1140/epjc/s10052-020-08581-9
Regular Article – Theoretical Physics
Inflation near a metastable de Sitter vacuum from moduli stabilisation
1
Laboratoire de Physique Théorique et Hautes Energies-LPTHE, Sorbonne Université, CNRS, 4 Place Jussieu, 75005, Paris, France
2
Albert Einstein Center, Institute for Theoretical Physics, University of Bern, Sidlerstrasse 5, 3012, Bern, Switzerland
3
Physics Department, University of Ioannina, 45110, Ioannina, Greece
Received:
27
July
2020
Accepted:
19
October
2020
Published online:
2
November
2020
We study the cosmological properties of a metastable de Sitter vacuum obtained recently in the framework of type IIB flux compactifications in the presence of three D7-brane stacks, based on perturbative quantum corrections at both world-sheet and string loop level that are dominant at large volume and weak coupling. In the simplest case, the model has one effective parameter controlling the shape of the potential of the inflaton which is identified with the volume modulus. The model provides a phenomenological successful small-field inflation for a value of the parameter that makes the minimum very shallow and near the maximum. The horizon exit is close to the inflection point while most of the required e-folds of the Universe expansion are generated near the minimum, with a prediction for the ratio of tensor-to-scalar primordial fluctuations 
. Despite its shallowness, the minimum turns out to be practically stable. We show that it can decay only through the Hawking–Moss instanton leading to an extremely long decay rate. Obviously, in order to end inflation and obtain a realistic model, new low-energy physics is needed around the minimum, at intermediate energy scales of order 
GeV. An attractive possibility is by introducing a “waterfall” field within the framework of hybrid inflation.
© The Author(s) 2020
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