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31
Fourdimensional String Compactifications with DBranes, Orientifolds and Fluxes
"... This review article provides a pedagogical introduction into various classes of chiral string compactifications to four dimensions with Dbranes and fluxes. The main concern is to provide all necessary technical tools to explicitly construct fourdimensional orientifold vacua, with the final aim to ..."
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Cited by 147 (18 self)
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This review article provides a pedagogical introduction into various classes of chiral string compactifications to four dimensions with Dbranes and fluxes. The main concern is to provide all necessary technical tools to explicitly construct fourdimensional orientifold vacua, with the final aim to come as close as possible to the supersymmetric Standard Model. Furthermore, we outline the available methods to derive the resulting fourdimensional effective action. Finally, we summarize recent attempts to address the
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.
Lifting DInstanton Zero Modes by Recombination and Background Fluxes
, 2007
"... We study the conditions under which Dbrane instantons in Type II orientifold compactifications generate a nonperturbative superpotential. If the instanton is noninvariant under the orientifold action, it carries four instead of the two Goldstone fermions required for superpotential contributions. ..."
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Cited by 40 (15 self)
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We study the conditions under which Dbrane instantons in Type II orientifold compactifications generate a nonperturbative superpotential. If the instanton is noninvariant under the orientifold action, it carries four instead of the two Goldstone fermions required for superpotential contributions. Unless these are lifted, the instanton can at best generate higher fermionic Fterms of BeasleyWitten type. We analyse two strategies to lift the additional zero modes. First we discuss the process of instantonic brane recombination in Type IIA orientifolds. We show that in some cases charge invariance of the measure enforces the presence of further zero modes which, unlike the Goldstinos, cannot be absorbed. In other cases, the instanton exhibits reparameterisation zero modes after recombination and a superpotential is generated if these are lifted by suitable closed or open string couplings. In the second part of the paper we address lifting the extra Goldstinos of D3brane instantons by supersymmetric threeform background fluxes in Type IIB orientifolds. This requires nontrivial gauge flux on the instanton. Only if the part of the fermionic action linear in the gauge flux survives the orientifold projection can the extra Goldstinos be lifted.
Flux algebra, Bianchi identities and FreedWitten . . .
, 2009
"... We discuss the structure of 4D gauged supergravity algebras corresponding to globally nongeometric compactifications of Ftheory, admitting a local geometric description in terms of 10D supergravity. By starting with the well known algebra of gauge generators associated to nongeometric type IIB flux ..."
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Cited by 25 (2 self)
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We discuss the structure of 4D gauged supergravity algebras corresponding to globally nongeometric compactifications of Ftheory, admitting a local geometric description in terms of 10D supergravity. By starting with the well known algebra of gauge generators associated to nongeometric type IIB fluxes, we derive a full algebra containing all, closed RR and NSNS, geometric and nongeometric dual fluxes. We achieve this generalization by a systematic application of SL(2, Z) duality transformations and by taking care of the spinorial structure of the fluxes. The resulting algebra encodes much information about the higher dimensional theory. In particular, tadpole equations and Bianchi identities are obtainable as Jacobi identities of the algebra. When a sector of magnetized (p,q) 7branes is included, certain closed axions are gauged by the U(1) transformations on the branes. We indicate how the diagonal gauge generators of the branes can be incorporated into the full algebra, and show that FreedWitten constraints and tadpole cancellation conditions for (p,q) 7branes can be described as Jacobi identities satisfied by the algebra mixing bulk and brane gauge generators.
On general flux backgrounds with localized sources
 JHEP 0711 (2007) 082 [arXiv:0710.2551 [hepth
"... Abstract: We derive new consistency conditions for string compactifications with generic fluxes (RR, NSNS, geometrical) and localized sources (Dbranes, NSbranes, KKmonopoles). The constraints are all related by string dualities and share a common origin in Mtheory. We also find new sources of ins ..."
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Cited by 19 (2 self)
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Abstract: We derive new consistency conditions for string compactifications with generic fluxes (RR, NSNS, geometrical) and localized sources (Dbranes, NSbranes, KKmonopoles). The constraints are all related by string dualities and share a common origin in Mtheory. We also find new sources of instabilities. We discuss the importance of these conditions for the consistency of the effective action and for the study of interpolating solutions between vacua. Keywords: Flux compactifications, Dbranes, Intersecting brane models, M theory. Contents
Open string wavefunctions in flux compactifications
, 2009
"... We consider compactifications of type I supergravity on manifolds with SU(3) structure, in the presence of RR fluxes and magnetized D9branes, and analyze the generalized Dirac and LaplaceBeltrami operators associated to the D9brane worldvolume fields. These compactifications are Tdual to standar ..."
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Cited by 18 (5 self)
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We consider compactifications of type I supergravity on manifolds with SU(3) structure, in the presence of RR fluxes and magnetized D9branes, and analyze the generalized Dirac and LaplaceBeltrami operators associated to the D9brane worldvolume fields. These compactifications are Tdual to standard type IIB toroidal orientifolds with NSNS and RR 3form fluxes and D3/D7 branes. By using techniques of representation theory and harmonic analysis, the spectrum of open string wavefunctions can be computed for Lie groups and their quotients, as we illustrate with explicit twisted tori examples. We find a correspondence between irreducible unitary representations of the KaloperMyers algebra and families of KaluzaKlein excitations. We perform the computation of 2 and 3point couplings for matter fields in the above flux compactifications, and compare our results with those of 4d effective supergravity.
Towards a realistic type IIA T 6 /Z4 orientifold model with background fluxes. I: Moduli stabilization
 J. High Energy Phys
"... We apply the methods of DeWolfe et al. [hepth/0505160] to a T 6 /Z4 orientifold model. This is the first step in an attempt to build a phenomenologically interesting metastable de There have been some longstanding, unsolved problems when it comes to realistic model building within the framework of ..."
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Cited by 2 (1 self)
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We apply the methods of DeWolfe et al. [hepth/0505160] to a T 6 /Z4 orientifold model. This is the first step in an attempt to build a phenomenologically interesting metastable de There have been some longstanding, unsolved problems when it comes to realistic model building within the framework of CalabiYau (CY) compactifications of superstring theories, namely • supersymmetry breaking,
Toroidal Orientifolds in IIA with General NSNS Fluxes
 JHEP
"... Type IIA toroidal orientifolds offer a promising toolkit for model builders, especially when one includes not only the usual fluxes from NSNS and RR field strengths, but also fluxes that are Tdual to the NSNS threeform flux. These new ingredients are known as metric fluxes and nongeometric flu ..."
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Cited by 2 (1 self)
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Type IIA toroidal orientifolds offer a promising toolkit for model builders, especially when one includes not only the usual fluxes from NSNS and RR field strengths, but also fluxes that are Tdual to the NSNS threeform flux. These new ingredients are known as metric fluxes and nongeometric fluxes, and can help stabilize moduli or can lead to other new features. In this paper we study two approaches to these constructions, by effective field theory or by toroidal fibers twisted over a toroidal base. Each approach leads us to important observations, in particular the presence of Dterms in the fourdimensional effective potential in some cases, and a more subtle treatment of the quantization of the general NSNS fluxes. Though our methods are general, we illustrate each approach on the example of an orientifold
On moduli and effective theory of N = 1 warped flux compactifications
, 902
"... The moduli space of N = 1 type II warped compactions to flat space with generic internal fluxes is studied. Using the underlying integrable generalized complex structure that characterizes these vacua, the different deformations are classified by Htwisted generalized cohomologies and identified wit ..."
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Cited by 2 (0 self)
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The moduli space of N = 1 type II warped compactions to flat space with generic internal fluxes is studied. Using the underlying integrable generalized complex structure that characterizes these vacua, the different deformations are classified by Htwisted generalized cohomologies and identified with chiral and linear multiplets of the effective fourdimensional theory. The Kähler potential for chiral fields corresponding to classically flat moduli is discussed. As an application of the general results, type IIB warped CalabiYau compactifications and other SU(3)structure subcases are considered in more detail.