Model-independent properties and cosmological implications of the dilaton and moduli sectors of 4D strings

Carlos, B. de; Casas, J.A.; Quevedo, Fernando; Roulet, Esteban

doi:10.1016/0370-2693(93)91538-x

Cited by 510 publications

(567 citation statements)

References 45 publications

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“…Such an inflationary regime would iron out any wrinkles in the two large extra dimensions as well as from the four dimensions we see, effectively removing the dangerous KK modes from the initial conditions of the later Universe. It would also dilute otherwise the influence of the problematic moduli generically responsible for the Cosmological Modulus Problem [66][67][68]. A viable cosmology could follow if this is followed by a reheat on the SM brane to temperatures not too far above nucleosynthesis temperatures, with the explanation for dark matter (and possibly baryons) potentially arising as relics from the reheating process.…”

Section: Jhep10(2011)119mentioning

confidence: 99%

Anisotropic modulus stabilisation: strings at LHC scales with micron-sized extra dimensions

Cicoli

Burgess

Quevedo

2011

J. High Energ. Phys.

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151

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We construct flux-stabilised Type IIB string compactifications whose extra dimensions have very different sizes, and use these to describe several types of vacua with a TeV string scale. Because we can access regimes where two dimensions are hierarchically larger than the other four, we find examples where two dimensions are micron-sized while the other four are at the weak scale in addition to more standard examples with all six extra dimensions equally large. Besides providing ultraviolet completeness, the phenomenology of these models is richer than vanilla large-dimensional models in several generic ways: (i) they are supersymmetric, with supersymmetry broken at sub-eV scales in the bulk but only nonlinearly realised in the Standard Model sector, leading to no MSSM superpartners for ordinary particles and many more bulk missing-energy channels, as in supersymmetric large extra dimensions (SLED); (ii) small cycles in the more complicated extra-dimensional geometry allow some KK states to reside at TeV scales even if all six extra dimensions are nominally much larger; (iii) a rich spectrum of string and KK states at TeV scales; and (iv) an equally rich spectrum of very light moduli exist having unusually small (but technically natural) masses, with potentially interesting implications for cosmology and astrophysics that nonetheless evade new-force constraints. The hierarchy problem is solved in these models because the extra-dimensional volume is naturally stabilised at exponentially large values: the extra dimensions are Calabi-Yau geometries with a 4D K3 or T 4 -fibration over a Open Access doi:10.1007/JHEP10 (2011)119 JHEP10 (2011)119 2D base, with moduli stabilised within the well-established LARGE-Volume scenario. The new technical step is the use of poly-instanton corrections to the superpotential (which, unlike for simpler models, are likely to be present on K3 or T 4 -fibered Calabi-Yau compactifications) to obtain a large hierarchy between the sizes of different dimensions. For several scenarios we identify the low-energy spectrum and briefly discuss some of their astrophysical, cosmological and phenomenological implications.

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Section: Jhep10(2011)119mentioning

confidence: 99%

Anisotropic modulus stabilisation: strings at LHC scales with micron-sized extra dimensions

Cicoli

Burgess

Quevedo

2011

J. High Energ. Phys.

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151

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“…For the intermediate scale, the volume modulus τ 5 is relatively light. Its mass does not present a problem with fifth force experiments but may be problematic in a cosmological context [101,102]. Finally, for TeV scale gravity all moduli are very light.…”

Section: Properties Of the Spectrummentioning

confidence: 99%

Moduli stabilisation and applications in IIB string theory

Conlon¹

2007

Fortschritte der Physik

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SummaryString compactifications represent the most promising approach towards unifying general relativity with particle physics. However, naive compactifications give rise to massless particles (moduli) which would mediate unobserved longrange forces, and it is therefore necessary to generate a potential for the moduli.In the introductory chapters I review this problem and recall how in IIB compactifications the dilaton and complex structure moduli can be stabilised by 3-form fluxes. There exist very many possible discrete flux choices which motivates the use of statistical techniques to analyse this discretuum of choices. Such approaches generate formulae predicting the distribution of vacua and I describe numerical tests of these formulae on the Calabi-Yau P 4[1,1,2,2,6] . Stabilising the Kähler moduli requires nonperturbative superpotential effects. I review the KKLT construction and explain why this must in general be supplemented with perturbative Kähler corrections. I show how the incorporation of such corrections generically leads to non-supersymmetric minima at exponentially large volumes, giving a detailed account of the α ′ expansion and its relation to Kähler corrections. I illustrate this with explicit computations for the 1,1,6,9] . The next part of the thesis examines phenomenological applications of this construction. I first describe how the magnitude of the soft supersymmetry parameters may be computed. In the large-volume models the gravitino mass and soft terms are volume-suppressed. As we naturally have V ≫ 1, this gives a dynamical solution of the hierarchy problem. I also demonstrate the existence of a fine structure in the soft terms, with gaugino masses naturally lighter than the gravitino mass by a factor ln M P m 3/2 . A second chapter gives a detailed analysis of the relationship of moduli stabilisation to the QCD axions relevant to the strong CP problem, proving a no-go theorem on the compatibility of a QCD axion with supersymmetric moduli stabilisation. I describe how QCD axions can coexist with nonsupersymmetric perturbative stabilisation and how the large-volume models naturally contain axions with decay constants that are phenomenologically allowed and satisfy the appealing relationship f 2 a ∼ M P M susy . A further chapter describe how a simple and predictive inflationary model can be built in the context of the above large-volume construction, using the no-scale Kähler potential to avoid the η problem.I finally conclude, summarising the phenomenological scenario and outlining the prospects for future work.

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“…This issue is also crucial to understand all the main features of the low-energy effective field theory, since both the gauge and the Yukawa couplings depend on the vacuum expectation value (VEV) of the moduli. There is also a cosmological constraint over the moduli masses, m mod ≥ 10 TeV, so that they decay before baryogenesis evading the cosmological moduli problem [63,64,65].…”

Section: Compactification Of Extra Dimensionsmentioning

confidence: 99%

“…Let us now explain two general and important obstacles in string inflation modelbuilding: the cosmological moduli problem [63,64,65] and the η problem [195].…”

Section: Challenges For String Inflationmentioning

confidence: 99%

“…On the other hand, if χ is somewhat heavier, it will have decayed during or after Big Bang Nucleosynthesis, spoiling the delicate predictions of the light element abundances (such as those of 4 He and D nuclei). To avoid this 'cosmological moduli problem' [63,64,65], one must therefore arrange that m χ > 10 TeV, and preferably that m 2 χ ≫ H 2 . At present there is no compelling solution to this problem.…”

Section: The Cosmological Moduli Problemmentioning

confidence: 99%

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String loop moduli stabilisation and cosmology in IIB flux compactifications

Cicoli¹

2010

Fortschritte der Physik

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We present a detailed review of the moduli stabilisation mechanism and possible cosmological implications of the LARGE Volume Scenario (LVS) that emerges naturally in the context of type IIB Calabi‐Yau flux compactifications. After a quick overview of physics beyond the Standard Model, we present string theory as the most promising candidate for a consistent theory of quantum gravity. We then give a pedagogical introduction to type IIB compactifications on Calabi‐Yau orientifolds where most of the moduli are stabilised by turning on background fluxes. However in order to fix the Kähler moduli one needs to consider several corrections beyond the leading order approximations. After presenting a survey of all the existing solutions to this problem, we derive the topological conditions on an arbitrary Calabi‐Yau to obtain the LVS since it requires no fine‐tuning of the fluxes and provides a natural solution of the hierarchy problem. After performing a systematic study of the behaviour of string loop corrections for general type IIB compactifications, we show how they play a crucial rôle to achieve full Kähler moduli stabilisation in the LVS. Before examining the possible cosmological implication of these scenarios, we present a broad overview of string cosmology. We then notice how, in the case of K3‐fibrations, string loop corrections give rise naturally to an inflationary model which yields observable gravity waves. We finally study the finite‐temperature behaviour of the LVS and discuss prospects for future work.

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Model-independent properties and cosmological implications of the dilaton and moduli sectors of 4D strings

Cited by 510 publications

References 45 publications

Anisotropic modulus stabilisation: strings at LHC scales with micron-sized extra dimensions

Anisotropic modulus stabilisation: strings at LHC scales with micron-sized extra dimensions

Moduli stabilisation and applications in IIB string theory

String loop moduli stabilisation and cosmology in IIB flux compactifications

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