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73
Largevolume flux compactifications: Moduli spectrum and D3/D7 soft supersymmetry breaking
 SYSTEMATICS OF MODULI STABILISATION IN CALABIYAU FLUX COMPACTIFICATIONS,” JHEP 0503 (2005) 007 [ARXIV:HEPTH/0502058]. – 42
, 2005
"... We present an explicit calculation of the spectrum of a general class of string models, corresponding to CalabiYau flux compactifications with h1,2> h1,1> 1 with leading perturbative and nonperturbative corrections, in which all geometric moduli are stabilised as in hepth/0502058. The volum ..."
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Cited by 129 (20 self)
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We present an explicit calculation of the spectrum of a general class of string models, corresponding to CalabiYau flux compactifications with h1,2> h1,1> 1 with leading perturbative and nonperturbative corrections, in which all geometric moduli are stabilised as in hepth/0502058. The volume is exponentially large, leading to a range of string scales from the Planck mass to the TeV scale, realising for the first time the large extra dimensions scenario in string theory. We provide a general analysis of the relevance of perturbative and nonperturbative effects and the regime of validity of the effective field theory. We compute the spectrum in the moduli sector finding a hierarchy of masses depending on inverse powers of the volume. We also compute soft supersymmetry breaking terms for particles living on D3 and D7 branes. We find a hierarchy of soft terms corresponding to ‘volume dominated ’ Fterm supersymmetry breaking. Fterms for Kähler moduli dominate both those for dilaton and complex
Nonperturbative superpotentials in Ftheory and string duality
, 2005
"... We use openclosed string duality between Ftheory on K3 × K3 and type II strings on CY manifolds without branes to study nonperturbative superpotentials in generalized flux compactifications. On the Ftheory side we obtain the full flux potential including D3instanton contributions and show that ..."
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Cited by 45 (2 self)
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We use openclosed string duality between Ftheory on K3 × K3 and type II strings on CY manifolds without branes to study nonperturbative superpotentials in generalized flux compactifications. On the Ftheory side we obtain the full flux potential including D3instanton contributions and show that it leads to an explicit and simple realization of the three ingredients of the KKLT model for stringy dS vacua. The D3instanton contribution is highly nontrivial, can be systematically computed including the determinant factors and demonstrates that a particular flux lifts very effectively zero modes on the instanton. On the closed string side, we describe a generalization of the GukovVafaWitten superpotential for type II strings on generalized CY manifolds, depending on all moduli multiplets.
Generalized nonsupersymmetric flux vacua
, 2008
"... We discuss a novel strategy to construct 4D N = 0 stable flux vacua of type II string theory, based on the existence of BPS bounds for probe Dbranes in some of these backgrounds. In particular, we consider compactifications where Dbranes filling the 4D spacetime obey the same BPS bound as they ..."
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Cited by 45 (11 self)
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We discuss a novel strategy to construct 4D N = 0 stable flux vacua of type II string theory, based on the existence of BPS bounds for probe Dbranes in some of these backgrounds. In particular, we consider compactifications where Dbranes filling the 4D spacetime obey the same BPS bound as they would in an N = 1 compactification, while other Dbranes, like those appearing as domain walls from the 4D perspective, can no longer be BPS. We construct a subfamily of such backgrounds giving rise to 4D N = 0 Minkowski noscale vacua, generalizing the wellknown case of type IIB on a warped CalabiYau. We provide several explicit examples of these constructions, and compute quantities of phenomenological interest like fluxinduced soft terms on Dbranes. Our results have a natural, simple description in the language of Generalized Complex Geometry, and in particular in terms of Dbrane generalized calibrations. Finally, we extend the integrability theorems for 10D supersymmetric type II backgrounds to the N = 0 case and use the results to construct a new class of N = 0 AdS4 compactifications.
Towards an explicit model of dbrane inflation
"... We present a detailed analysis of an explicit model of warped Dbrane inflation, incorporating the effects of moduli stabilization. We consider the potential for D3brane motion in a warped conifold background that includes fluxes and holomorphicallyembedded D7branes involved in moduli stabilizati ..."
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Cited by 34 (3 self)
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We present a detailed analysis of an explicit model of warped Dbrane inflation, incorporating the effects of moduli stabilization. We consider the potential for D3brane motion in a warped conifold background that includes fluxes and holomorphicallyembedded D7branes involved in moduli stabilization. Although the D7branes significantly modify the inflaton potential, they do not correct the quadratic term in the potential, and hence do not cause a uniform change in the slowroll parameter η. Nevertheless, we present a simple example based on the Kuperstein embedding of D7branes, z1 = constant, in which the potential can be finetuned to be sufficiently flat for inflation. To derive this result, it is essential to incorporate the fact that the compactification volume changes slightly as the D3brane moves. We stress that the compactification geometry dictates certain relationships among the parameters in the inflaton Lagrangian, and these microscopic constraints impose severe restrictions on the space of possible models. We note that the shape of the final inflaton potential differs from projections given in earlier studies: in configurations where inflation occurs, it does so near an inflection point. Finally, we comment on the difficulty of making precise cosmological predictions in this scenario. This is the companion paper to [1].
MODELS OF PARTICLE PHYSICS FROM TYPE IIB STRING THEORY AND FTHEORY: A REVIEW
, 2012
"... We review particle physics model building in type IIB string theory and Ftheory. This is a region in the landscape where in principle many of the key ingredients required for a realistic model of particle physics can be combined successfully. We begin by reviewing moduli stabilisation within this f ..."
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Cited by 33 (4 self)
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We review particle physics model building in type IIB string theory and Ftheory. This is a region in the landscape where in principle many of the key ingredients required for a realistic model of particle physics can be combined successfully. We begin by reviewing moduli stabilisation within this framework and its implications for supersymmetry breaking. We then review model building tools and developments in the weakly coupled type IIB limit, for both local D3branes at singularities and global models of intersecting D7branes. Much of recent model building work has been in the strongly coupled regime of Ftheory due to the presence of exceptional symmetries which allow for the construction of phenomenologically appealing Grand Unified Theories. We review both local and global Ftheory model building starting from the fundamental concepts and tools regarding how the gauge group, matter sector and operators arise, and ranging to detailed phenomenological properties explored in the literature.
Modulusdominated SUSYbreaking soft terms in Ftheory and their test at LHC
, 2008
"... We study the general patterns of SUSYbreaking soft terms arising under the assumption of Kahler moduli dominated SUSYbreaking in string theory models. Insisting that all MSSM gauginos get masses at leading order and that the top Yukawa coupling is of order the gauge coupling constant identifies th ..."
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Cited by 27 (0 self)
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We study the general patterns of SUSYbreaking soft terms arising under the assumption of Kahler moduli dominated SUSYbreaking in string theory models. Insisting that all MSSM gauginos get masses at leading order and that the top Yukawa coupling is of order the gauge coupling constant identifies the class of viable models. These are models in which the SM fields live either in the bulk or at the intersection of local sets of Type IIB D7branes or their Ftheory relatives. General arguments allow us to compute the dependence of the Kahler metrics of MSSM fields on the local Kahler modulus of the brane configuration in the large moduli approximation. We illustrate this study in the case of toroidal/orbifold orientifolds but discuss how the findings generalize to the Ftheory case which is more naturally compatible with coupling unification. Only three types of 7brane configurations are possible, leading each of them to very constrained patterns of soft terms for the MSSM. We study their consistency with radiative electroweak symmetry breaking and other phenomenological constraints. We find that essentially only the configuration corresponding to intersecting 7branes is compatible with all present experimental
Computational complexity of the landscape
 I
"... Abstract: We study the computational complexity of the physical problem of finding vacua of string theory which agree with data, such as the cosmological constant, and show that such problems are typically NP hard. In particular, we prove that in the BoussoPolchinski model, the problem is NP comple ..."
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Cited by 25 (2 self)
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Abstract: We study the computational complexity of the physical problem of finding vacua of string theory which agree with data, such as the cosmological constant, and show that such problems are typically NP hard. In particular, we prove that in the BoussoPolchinski model, the problem is NP complete. We discuss the issues this raises and the possibility that, even if we were to find compelling evidence that some vacuum of string theory describes our universe, we might never be able to find that vacuum explicitly. In a companion paper, we apply this point of view to the question of how early cosmology might select a vacuum. Contents
General Analysis of LARGE Volume Scenarios with String Loop Moduli Stabilisation,” 0805.1029
"... Abstract: We study the topological conditions for general CalabiYaus to get a nonsupersymmetric AdS exponentially large volume minimum of the scalar potential in flux compactifications of IIB string theory. We show that negative Euler number and the existence of at least one blowup mode resolving ..."
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Cited by 23 (3 self)
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Abstract: We study the topological conditions for general CalabiYaus to get a nonsupersymmetric AdS exponentially large volume minimum of the scalar potential in flux compactifications of IIB string theory. We show that negative Euler number and the existence of at least one blowup mode resolving pointlike singularities are necessary and sufficient conditions for moduli stabilisation with exponentially large volumes. We also analyse the general effects of string loop corrections on this scenario. While the combination of α ′ and nonperturbative corrections are sufficient to stabilise blowup modes and the overall volume, quantum corrections are needed to stabilise other directions transverse to the overall volume. This allows exponentially large volume minima to be realised for fibration CalabiYaus, with the various moduli of the fibration all being stabilised at exponentially large values. String loop corrections may also play a role in stabilising 4cycles which support chiral matter and cannot enter directly into the nonperturbative superpotential. We illustrate these ideas by studying the scalar potential for various CalabiYau threefolds including K3 fibrations and briefly discuss the potential phenomenological and
De Sitter String Vacua from Dilatondependent Nonperturbative Effects, JHEP 1206
, 2012
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Simple de Sitter Solutions
"... We present a framework for de Sitter model building in type IIA string theory, illustrated with specific examples. We find metastable dS minima of the potential for moduli obtained from a compactification on a product of two Nil threemanifolds (which have negative scalar curvature) combined with or ..."
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Cited by 18 (1 self)
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We present a framework for de Sitter model building in type IIA string theory, illustrated with specific examples. We find metastable dS minima of the potential for moduli obtained from a compactification on a product of two Nil threemanifolds (which have negative scalar curvature) combined with orientifolds, branes, fractional ChernSimons forms, and fluxes. As a discrete quantum number is taken large, the curvature, field strengths, inverse volume, and four dimensional string coupling become parametrically small, and the de Sitter Hubble scale can be tuned parametrically smaller than the scales of the moduli, KK, and winding mode masses. A subtle point in the construction is that although the curvature remains consistently weak, the circle fibers of the nilmanifolds become very small in this limit (though this is avoided in illustrative solutions at modest values of the parameters). In the simplest version of the construction, the heaviest moduli masses are parametrically of the same order as the lightest KK and winding masses. However, we provide a method for separating these marginally overlapping scales, and more generally the underlying supersymmetry of the model protects against large corrections to the lowenergy moduli potential. December