Results 1  10
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70
de Sitter string vacua from supersymmetric Dterms
 JHEP
, 2003
"... Abstract: We propose a new mechanism for obtaining de Sitter vacua in type IIB string theory compactified on (orientifolded) CalabiYau manifolds similar to those recently studied by Kachru, Kallosh, Linde and Trivedi (KKLT). dS vacuum appears in KKLT model after uplifting an AdS vacuum by adding an ..."
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Cited by 158 (19 self)
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Abstract: We propose a new mechanism for obtaining de Sitter vacua in type IIB string theory compactified on (orientifolded) CalabiYau manifolds similar to those recently studied by Kachru, Kallosh, Linde and Trivedi (KKLT). dS vacuum appears in KKLT model after uplifting an AdS vacuum by adding an antiD3brane, which explicitly breaks supersymmetry. We accomplish the same goal by adding fluxes of gauge fields within the D7branes, which induce a Dterm potential in the effective 4D action. In this way we obtain dS space as a spontaneously broken vacuum from a purely supersymmetric 4D action. We argue that our approach can be directly extended to heterotic string vacua, with the dilaton potential obtained from a combination of gaugino condensation and the Dterms generated by anomalous U(1) gauge groups. 1
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
Fluxes, moduli fixing and MSSMlike vacua in a simple IIA orientifold
, 2005
"... We study the effects of adding RR, NS and metric fluxes on a T6 /(Ω(−1) FLI3) Type IIA orientifold. By using the effective fluxinduced superpotential we obtain Minkowski or AdS vacua with broken or unbroken supersymmetry. In the Minkowski case some combinations of real moduli remain undetermined, w ..."
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Cited by 82 (4 self)
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We study the effects of adding RR, NS and metric fluxes on a T6 /(Ω(−1) FLI3) Type IIA orientifold. By using the effective fluxinduced superpotential we obtain Minkowski or AdS vacua with broken or unbroken supersymmetry. In the Minkowski case some combinations of real moduli remain undetermined, whereas all can be stabilized in the AdS solutions. Many flux parameters are available which are unconstrained by RR tadpole cancellation conditions allowing to locate the minima at large volume and small dilaton. We also find that in AdS supersymmetric vacua with metric fluxes, the overall flux contribution to RR tadpoles can vanish or have opposite sign to that of D6branes, allowing for new modelbuilding possibilities. In particular, we construct the first N=1 supersymmetric intersecting D6brane models with MSSMlike spectrum and with all closed string moduli stabilized. Some axionlike fields remain undetermined but they are precisely required to give Stückelberg masses to (potentially anomalous) U(1) brane fields. We show that the cancellation of the FreedWitten anomaly guarantees that the axions with fluxinduced masses are orthogonal to those giving masses to the U(1)’s. Cancellation of such anomalies also guarantees that the D6branes in our N=1 supersymmetric AdS vacua are calibrated so that they are forced to preserve one unbroken supersymmetry.
BPS Action and Superpotential for Heterotic String Compactifications with Fluxes
, 2003
"... We consider N = 1 compactifications to four dimensions of heterotic string theory in the presence of fluxes. We show that up to order O (α ′2) the associated action can be written as a sum of squares of BPSlike quantities. In this way we prove that the equations of motion are solved by backgrounds ..."
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Cited by 81 (4 self)
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We consider N = 1 compactifications to four dimensions of heterotic string theory in the presence of fluxes. We show that up to order O (α ′2) the associated action can be written as a sum of squares of BPSlike quantities. In this way we prove that the equations of motion are solved by backgrounds which fulfill the supersymmetry conditions and the Bianchi identities. We also argue for the expression of the related superpotential and discuss the radial modulus
Flux–induced Soft Supersymmetry Breaking in Chiral Type IIB Orientifolds with D3/D7–Branes
, 2004
"... We discuss supersymmetry breaking via 3–form fluxes in chiral supersymmetric type IIB orientifold vacua with D3 – and D7–branes. After a general discussion of possible choices of fluxes allowing for stabilizing of a part of the moduli, we determine the resulting effective action including all soft s ..."
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Cited by 79 (8 self)
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We discuss supersymmetry breaking via 3–form fluxes in chiral supersymmetric type IIB orientifold vacua with D3 – and D7–branes. After a general discussion of possible choices of fluxes allowing for stabilizing of a part of the moduli, we determine the resulting effective action including all soft supersymmetry breaking terms. We also extend the computation of our previous work [1] concerning the matter field metrics arising from various open string sectors, in particular focusing on the 1/2 BPS D3/D7–brane configuration. Afterwards, the F–theory lift of our constructions is investigated
Soft Supersymmetry Breaking in Calabiyau Orientifolds with Dbranes . . .
, 2003
"... In this paper we compute the N = 1 effective low energy action for a stack of N spacetime filling D3branes in generic type IIB CalabiYau orientifolds with nontrivial background fluxes by reducing the DiracBornInfeld and ChernSimons actions. Specifically, we determine the Kähler potential for ..."
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Cited by 79 (7 self)
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In this paper we compute the N = 1 effective low energy action for a stack of N spacetime filling D3branes in generic type IIB CalabiYau orientifolds with nontrivial background fluxes by reducing the DiracBornInfeld and ChernSimons actions. Specifically, we determine the Kähler potential for the excitations of the Dbrane including their couplings to all bulk moduli fields. In the effective theory, N = 1 supergravity is spontaneously broken by the presence of fluxes and we compute the induced soft supersymmetry breaking terms. We find an interesting structure in the resulting soft terms with generically universal soft scalar masses.
Systematics of moduli stabilisation in CalabiYau flux compactifications
 JHEP
, 2005
"... We study the large volume limit of the scalar potential in CalabiYau flux compactifications of type IIB string theory. Under general circumstances there exists a limit in which the potential approaches zero from below, with an associated nonsupersymmetric AdS minimum at exponentially large volume. ..."
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Cited by 73 (15 self)
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We study the large volume limit of the scalar potential in CalabiYau flux compactifications of type IIB string theory. Under general circumstances there exists a limit in which the potential approaches zero from below, with an associated nonsupersymmetric AdS minimum at exponentially large volume. Both this and its de Sitter uplift are tachyonfree, thereby fixing all Kähler and complex structure moduli. Also, for the class of vacua described in this paper, the gravitino mass is independent of the flux discretuum, whereas the ratio of the string scale to the 4d Planck scale is hierarchically small but flux dependent. The inclusion of α ′ corrections plays a crucial role in the structure of the potential. We illustrate these ideas through explicit computations for a particular CalabiYau manifold.
An open string landscape
 JHEP
, 2005
"... Abstract: The effect of fluxes on open string moduli is studied by analyzing the constraints imposed by supersymmetry on Dbranes in type IIB flux backgrounds. We show that generically the conditions of supersymmetry cannot be maintained when moving along the geometrical moduli space of the brane, s ..."
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Cited by 56 (3 self)
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Abstract: The effect of fluxes on open string moduli is studied by analyzing the constraints imposed by supersymmetry on Dbranes in type IIB flux backgrounds. We show that generically the conditions of supersymmetry cannot be maintained when moving along the geometrical moduli space of the brane, so that open string moduli are lifted. In specific examples, we find that there is a disconnected and discrete set of supersymmetric solutions to the open string equations of motion, which extends the familiar closed string landscape to the open string sector. Permanent addressContents
The Statistics of Supersymmetric Dbrane Models
, 2004
"... We investigate the statistics of the phenomenologically important Dbrane sector of string compactifications. In particular for the class of intersecting Dbrane models, we generalise methods known from number theory to determine the asymptotic statistical distribution of solutions to the tadpole ca ..."
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Cited by 53 (21 self)
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We investigate the statistics of the phenomenologically important Dbrane sector of string compactifications. In particular for the class of intersecting Dbrane models, we generalise methods known from number theory to determine the asymptotic statistical distribution of solutions to the tadpole cancellation conditions. Our approach allows us to compute the statistical distribution of gauge theoretic observables like the rank of the gauge group, the number of chiral generations or the probability of an SU(N) gauge factor. Concretely, we study the statistics of intersecting branes on T 2 and T 4 / Z2 and T 6 / Z2 × Z2 orientifolds. Intriguingly, we find a statistical correlation between the rank of the gauge group and the number of chiral generations. Finally, we combine the statistics of the gauge theory sector with the statistics of the flux sector and study how distributions of gauge theoretic quantities are affected.
Chiral Dbrane models with frozen open string moduli
, 2005
"... Most intersecting Dbrane vacua in the literature contain additional massless adjoint fields in their low energy spectrum. The existence of these additional fields make it difficult to obtain negative beta functions and, eventually, asymptotic freedom. We address this important issue for N = 1 inter ..."
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Cited by 46 (14 self)
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Most intersecting Dbrane vacua in the literature contain additional massless adjoint fields in their low energy spectrum. The existence of these additional fields make it difficult to obtain negative beta functions and, eventually, asymptotic freedom. We address this important issue for N = 1 intersecting Dbrane models, rephrasing the problems in terms of (open string) moduli stabilization. In particular, we consider a Z2 × Z2 orientifold construction where D6branes wrap rigid 3cycles and such extra adjoint fields do not arise. We derive the model building rules and consistency conditions for intersecting branes in this background, and provide N = 1 chiral vacua free of adjoint fields. More precisely, we construct a PatiSalamlike model whose SU(4) gauge group is asymptotically free. We also comment on the application of these results for obtaining gaugino condensation in chiral Dbrane models. Finally, we embed our constructions in the framework of flux compactification, and construct new classes of N = 1 and N = 0 chiral flux vacua.