Pixelated Dark Energy. Issue 11 (13th September 2019)

• Record Type: Journal Article
• Authors: Heckman, Jonathan J.; Lawrie, Craig; Lin, Ling; Sakstein, Jeremy; Zoccarato, Gianluca
• Is Part Of: Fortschritte der Physik. Volume 67:Issue 11(2019)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2019-09-13
• Subjects: dark energy -- F‐theory -- inflation -- superstring vacua; Physics -- Periodicals; 530.05
• DOI: 10.1002/prop.201900071
• Languages: English
• ISSNs: 0015-8208

Abstract

Abstract: We study the phenomenology of a recent string construction with a quantum mechanically stable dark energy. A mild supersymmetry protects the vacuum energy but also allows O ( 10 − 100 ) TeV scale superpartner masses. The construction is holographic in the sense that the 4D spacetime is generated from "spacetime pixels" originating from five‐branes wrapped over metastable five‐cycles of the compactification. The cosmological constant scales as Λ ∼ 1 / N in the pixel number. An instability in the construction leads to cosmic expansion. This also causes more five‐branes to wind up in the geometry, leading to a slowly decreasing cosmological constant which we interpret as an epoch of inflation followed by (pre‐)heating when a rare event occurs in which the number of pixels increases by an order one fraction. The sudden appearance of radiation triggers an exponential increase in the number of pixels. Dark energy has a time varying equation of state with w a = − 3 Ω m, 0 ( 1 + w 0 ) / 2, which is compatible with current bounds, and could be constrained further by future data releases. The pixelated nature of the Universe also implies a large‐ l cutoff on the angular power spectrum of cosmological observables with l max ∼ O ( N ) . We also use this pixel description to study the thermodynamics of de Sitter space, finding rough agreement with effective field theory considerations. Abstract : The phenomenology of a recent string construction with a quantum mechanically stable dark energy is studied. A mild supersymmetry protects the vacuum energy but also allows O(10−100) TeV scale superpartner masses. The construction is holographic in the sense that the 4D spacetime is generated from "spacetime pixels" originating from five‐branes wrapped over metastable five‐cycles of the compactification. The cosmological constant scales as Λ ∼ 1 ∕ N in the pixel number. An instability in the construction leads to cosmic expansion. This also causes more five‐branes to wind up in the geometry, leading to a slowly decreasing cosmological constant which is interpreted as an epoch of inflation followed by (pre‐)heating when a rare event occurs in which the number of pixels increases by an order one fraction. The sudden appearance of radiation triggers an exponential increase in the number of pixels. The pixelated nature of the universe also implies a large‐ l cutoff on the angular power spectrum of cosmological observables with l max ∼ O(N). This pixel description is used to study the thermodynamics of de Sitter space, finding rough agreement with effective field theory considerations.