Small Cosmological Constants in String Theory

Demirtas, Mehmet; Kim, Manki; McAllister, Liam; Moritz, Jakob; Rios-Tascon, Andres

doi:10.48550/arxiv.2107.09064

Cited by 9 publications

(16 citation statements)

References 79 publications

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“…14 Notice that in the string frame Re(TSM)| str = gsRe(TSM) ∼ O(1), implying that one should consider all perturbative and non-perturbative α corrections at string tree-level, except when |W0| 1 for those which come from 10-dimensional terms proportional to G 2n 3 with n > 1 [78]. However, as shown in [23], these α effects should induce just a subdominant shift of the KKLT minimum for |W0| 1.…”

Section: A 2-moduli Examples Datamentioning

confidence: 96%

“…In the first case, the strength of the gauge couplings is set by g s , and in the second by the Einstein frame volume of the 4-cycle wrapped by the D7-stack (which we denote as Re(T SM )). In the scenario at hand, however Kähler moduli stabilisation [23] gives 4π…”

Section: A More General Search Algorithmmentioning

confidence: 99%

“…The paper [17] presented an explicit choice of flux quanta in an orientifold of the Calabi-Yau obtained by considering a degree-18 hypersurface in CP [1,1,1,6,9] , which yielded |W 0 | ∼ 10 −8 (for earlier work on obtaining low values of |W 0 | see for example [20,21]). Not stopping at that, an explicit example with |W 0 | as low as 10 −95 was presented in [22,23]. Here, important advances were made in developing Kähler moduli stabilisation in this context.…”

Section: Introductionmentioning

confidence: 99%

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On the Search for Low $W_0$

Broeckel,

Cicoli,

Maharana

et al. 2021

Preprint

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The magnitude of the vacuum expectation value of the Gukov-Vafa-Witten superpotential |W 0 | plays a central role in the phenomenology of type IIB flux compactifications. Recent analytical constructions have shown that perturbatively flat vacua can be used to obtain very low values of |W 0 |. We present systematic algorithms to carry out exhaustive numerical searches for such vacua. We also analyse them in the statistical context, as part of the entire ensemble of type IIB flux vacua at low |W 0 |. Our preliminary analysis indicates that these perturbatively flat vacua are statistically sparse in the whole set of vacua at low |W 0 | as calculated by Denef and Douglas. Two-moduli examples are used to illustrate these more general findings in specific settings. We find that these simple cases are good examples for existence proofs but they do not feature a large statistical tuning freedom for phenomenological applications.

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Section: A 2-moduli Examples Datamentioning

confidence: 96%

Section: A More General Search Algorithmmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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On the Search for Low $W_0$

Broeckel,

Cicoli,

Maharana

et al. 2021

Preprint

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“…In particular |W 0 | ≤ 10 −16 combined with τ ∼ 10 14 may have the same effect as the values τ ∼ 10 26 (and W 0 ∼ O(1)) used here. It is worth mentioning that exponentially small flux superpotentials W 0 have been recently obtained by [114] in a natural way. Furthermore, for the Standard Model anti-brane the amount of warping provided by the fluxes can also be used in order to get the appropriate scales.…”

Section: Uv Embeddingsmentioning

confidence: 99%

Yoga Dark Energy: Natural Relaxation and Other Dark Implications of a Supersymmetric Gravity Sector

Burgess,

Dineen,

Quevedo

2021

Preprint

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We construct a class of 4D 'yoga' (naturally relaxed) models for which the vacuum energies of heavy particles do not gravitate. The models contain three ingredients: (i) a relaxation mechanism driven by a scalar field (the 'relaxon'), (ii) a very supersymmetric gravity sector coupled to the Standard Model in which supersymmetry is non-linearly realised, and (iii) an accidental approximate scale invariance expressed through the presence of a low-energy dilaton supermultiplet. All three are common in higher-dimensional and string constructions. Although none suffices on its own, taken together they predict a current Dark Energy density that is of order (M 2 W /M p ) 4 and a gravitino mass of order M 3 W /M 2 p , with M W , M p the weak and Planck scales respectively. The dilaton's vev τ determines the weak scale M W ∼ M p / √ τ and because the relevant part of the scalar potential arises as a function of ln τ it stabilizes τ in a local de Sitter minimum with exponentially large fields obtained using input parameters no larger than O(60), thereby explaining both the size of the electroweak hierarchy and the cosmological constant. Scale invariance implies the dilaton couples to matter like a Brans-Dicke scalar with coupling large enough to be naively ruled out by solar-system tests of gravity. Yet because it comes paired with an axion it escapes fifth-force bounds through the novel screening mechanism described in ArXiV:2110.10352. Cosmological axio-dilaton evolution provides a natural quintessence model for Dark Energy, whose evolution might realize recent proposals to resolve the Hubble tension, and whose axion contributes to Dark Matter. We summarize some of the remaining challenges, comment on implications for inflation and sketch possible UV completions of our approach.

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“…The choice of higher-dimensional fluxes shows up in the low-energy 4D theory in several ways. First, (0, 3) fluxes induce a non-trivial superpotential w 0 ∈ W that is generically order unity (in Planck units) but can be arranged to take larger -or extremely small [39] -values. Second, since fluxes fix the string dilaton field S they provide a 'discretuum' of possible values for the string coupling constant g s ∼ s −1 in the 4D theory.…”

Section: Iib Modulus Stabilizationmentioning

confidence: 99%

RG-Induced Modulus Stabilization: Perturbative de Sitter Vacua and Improved $\hbox{D3}$-$\overline{\hbox{D3}}$ Inflation

Burgess,

Quevedo

2022

Preprint

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We propose a new mechanism that adapts to string theory a perturbative method for stabilizing moduli without leaving the domain of perturbative control, thereby evading the 'Dine-Seiberg' problem. The only required nonperturbative information comes from the standard renormalization-group resummation of leading logarithms that allow us simultaneously to work to a fixed order in the perturbative parameter α and to all orders in α ln τ where τ is a large extra-dimensional modulus. The resulting potential is naturally minimized for moduli of order τ ∼ e 1/α and so can be exponentially large given O(10) input parameters. The mechanism relies on accidental low-energy scaling symmetries known to be generic and so is robust against UV details. The resulting compactifications generically break supersymmetry and 4D de Sitter solutions are relatively easy to achieve without additional uplifting. Variations on the theme lead to inflationary scenarios for which the size of the stabilized moduli differ significantly before and after inflation and so provide a dynamical mechanism whereby inflationary scales are much larger than late-time physical (e.g. supersymmetry breaking) scales, with this hierarchy contingent on past cosmic evolution with the inflaton playing a secondary late-time role as a relaxation field. We apply this formalism to warped D3-D3 inflation using non-linearly realized supersymmetry to describe the antibrane tension and the Coulomb interaction, and show how doing so our perturbative modulus stabilization mechanism evades the η-problem that usually plagues this scenario. We speculate about the relevance of our formalism to tachyon condensation at later stages of brane-antibrane annihilation.

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Small Cosmological Constants in String Theory

Cited by 9 publications

References 79 publications

On the Search for Low $W_0$

On the Search for Low $W_0$

Yoga Dark Energy: Natural Relaxation and Other Dark Implications of a Supersymmetric Gravity Sector

RG-Induced Modulus Stabilization: Perturbative de Sitter Vacua and Improved $\hbox{D3}$-$\overline{\hbox{D3}}$ Inflation

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