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| Paper IPM / P / 15412 |
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| Abstract: | |
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The difficulty of building metastable vacua in string theory, has led some to conjecture that, in the string theory landscape, potentials satisfy |∇V/V| ≥ c ∼ O(1). This condition, which is supported by different explicit constructions, suggests that the EFTs which lead to metastable de-Sitter vacua belong to what is dubbed as swampland. This condition endangers the paradigm of single field inflation. In this paper, we show how scalar excited initial states cannot rescue single field inflation, as they produce large local non-gaussianity, which is in conflict with the Planck upper bounds. Instead, we demonstrate that one can salvage single field inflation from the swampland using excited initial states for the tensor perturbations, which produce only large flattened non-gaussianity in the tensor bispectrum. We comment on possible methods one can prepare such excited initial conditions for the tensor perturbations.
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