F‐theory and Dark Energy

Self Cite

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 wa=−3normalΩm,0false(1+w0false)/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 ∼Ofalse(Nfalse). We also use this pixel description to study the thermodynamics of de Sitter space, finding rough agreement with effective field theory considerations.

{double-struckR}_{time} \times S^{3}

(i.e.…”

Section: Introductionmentioning

confidence: 99%

{double-struckR}_{time} \times S^{3}

(i.e. the Universe is closed) and represents a cosmology in which dark energy (with equation of state

w = - 1

) balances against positive spatial curvature and a stiff fluid (with equation of state

w = + 1

).…”

Section: Introductionmentioning

confidence: 99%

ρ_{curvature} \sim - \frac{1}{a^{2}}, ρ_{normalΛ} \sim \frac{1}{N}, ρ_{stiff} \sim \frac{N^{2}}{a^{6}},

with a being the scale factor of a closed FRW spacetime:

d s_{FRW}^{2} = - d t^{2} + a^{2} false(t false) d {normalΩ}_{S^{3}}^{2} .

Section: Introductionmentioning

confidence: 99%

“…This leads to a UV‐complete model of dark energy in which zero point (vacuum) energies from all quantum sectors automatically cancel. In [] this was referred to as “

N = 1 / 2

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Pixelated Dark Energy

Heckman

Lawrie

Lin

et al. 2019

Self Cite

Further Refining the de Sitter Swampland Conjecture

Andriot

Roupec

2019

131

158

We propose an alternative refined de Sitter conjecture. It is given by a natural condition on a combination of the first and second derivatives of the scalar potential. We derive our conjecture in the same weak coupling, semi‐classical regime where the previous refined de Sitter conjecture was derived, using the same tools together with a few more assumptions that we discuss. We further test and constrain free parameters in our conjecture using data points of a classical type IIA supergravity setup. Interestingly, our conjecture easily accommodates slow‐roll single field inflation with a concave potential, favored by observations. The standard quintessence potential is in tension with our new conjecture, and we thus propose a different type of quintessence model.

The Swampland: Introduction and Review

Palti

2019

902

1,097

The Swampland program aims to distinguish effective theories which can be completed into quantum gravity in the ultraviolet from those which cannot. This article forms an introduction to the field, assuming only a knowledge of quantum field theory and general relativity. It also forms a comprehensive review, covering the range of ideas that are part of the field, from the Weak Gravity Conjecture, through compactifications of String Theory, to the de Sitter conjecture.