2018/07/31 by Souvik Banerjee, Ulf Danielsson, Giuseppe Dibitetto +2 · 5 citations
Physics and Astronomy · #hep-th #gr-qc #hep-ph
paper · pdf · doi:10.1103/physrevlett.121.261301
published as Phys. Rev. Lett. 121, 261301 (2018) · v2: Published version. 6 pages, 3 figures
arxiv created 2019/01/02 · arxiv updated 2019/01/09
Recent developments in string compactifications demonstrate obstructions to the simplest constructions of low energy cosmologies with positive vacuum energy. The existence of obstacles to creating scale-separated de Sitter solutions indicates a UV/IR puzzle for embedding cosmological vacua in a unitary theory of quantum gravity. Motivated by this puzzle, we propose an embedding of positive energy Friedmann-Lemaitre-Robertson-Walker cosmology within string theory. Our proposal involves confining 4D gravity on a brane which mediates the decay from a non-supersymmetric false AdS5 vacuum to a true vacuum. In this way, it is natural for a 4D observer to experience an effective positive cosmological constant coupled to matter and radiation, avoiding the need for scale separation or a fundamental de Sitter vacuum.