On Algebraic Fiber Space Structures on a Calabi-Yau 3-Fold

Muia

Shukla

2016

J. High Energ. Phys.

We present concrete embeddings of fibre inflation models in globally consistent type IIB Calabi-Yau orientifolds with closed string moduli stabilisation. After performing a systematic search through the existing list of toric Calabi-Yau manifolds, we find several examples that reproduce the minimal setup to embed fibre inflation models. This involves Calabi-Yau manifolds with h 1,1 = 3 which are K3 fibrations over a P 1 base with an additional shrinkable rigid divisor. We then provide different consistent choices of the underlying brane set-up which generate a non-perturbative superpotential suitable for moduli stabilisation and string loop corrections with the correct form to drive inflation. For each Calabi-Yau orientifold setting, we also compute the effect of higher derivative contributions and study their influence on the inflationary dynamics.

Section: A Brief Reviewmentioning

confidence: 99%

Global embedding of fibre inflation models

Muia

Shukla

2016

J. High Energ. Phys.

“…The following sections describe two particular constructions, for which the potential energies are 2 The topology of the fibre can be determined by computing its Euler characteristic χ: if χ = 24 the fibre is a K3 surface whereas if χ = 0 the fibre is a T 4 surface [33,34].…”

Section: Type Iib Compactified On Fibered Calabi-yau Three-foldsmentioning

confidence: 99%

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

Burgess

Quevedo

2011

J. High Energ. Phys.

151

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.

“…Here we shall just focus on the simplest of such manifolds whose volume takes the form: 12) where t 1 is the volume of the P 1 base, τ 1 = λ 1 t 2 2 is the size of the K3 or T 4 fibre, and τ 3 = 3λ 2 t 2 3 controls the volume of a blow-up mode (the other four-cycle volume is given by τ 2 = 2λ 1 t 1 t 2 ). Notice that the fibre is a K3 surface if its Euler characteristic is χ = 24 whereas it is a T 4 divisor if χ = 0 [34]. We shall not specify the value of χ in order to be as generic as possible since our moduli stabilisation mechanism works in both cases.…”

Section: Fibred Compactificationsmentioning

confidence: 99%

Poly-instanton inflation

J. Cosmol. Astropart. Phys.

Pedro

Tasinato

2011

120

Abstract. We propose a new inflationary scenario in type IIB Calabi-Yau compactifications, where the inflaton is a Kähler modulus parameterising the volume of an internal four-cycle. The inflaton potential is generated via poly-instanton corrections to the superpotential which give rise to a naturally flat direction due to their double exponential suppression. Given that the volume mode is kept stable during inflation, all the inflaton-dependent higher dimensional operators are suppressed. Moreover, string loop effects can be shown to be negligible throughout all the inflationary dynamics for natural values of the underlying parameters. The model is characterised by a reheating temperature of the order T rh ≃ 10 6 GeV which requires N e ≃ 54 e-foldings of inflation. All the inflationary observables are compatible with current observations since the spectral index is n s ≃ 0.96, while the tensor-to-scalar ratio is r ≃ 10 −5 . The volume of the Calabi-Yau is of order 10 3 in string units, corresponding to an inflationary scale around 10 15 GeV.