Results 1  10
of
59
Distributions of flux vacua
 JHEP
"... Abstract: We give results for the distribution and number of flux vacua of various types, supersymmetric and nonsupersymmetric, in IIb string theory compactified on CalabiYau manifolds. We compare this with related problems such as counting attractor points. Contents ..."
Abstract

Cited by 165 (16 self)
 Add to MetaCart
(Show Context)
Abstract: We give results for the distribution and number of flux vacua of various types, supersymmetric and nonsupersymmetric, in IIb string theory compactified on CalabiYau manifolds. We compare this with related problems such as counting attractor points. Contents
Towards inflation in string theory
 JCAP
, 2003
"... We investigate the embedding of brane inflation into stable compactifications of string theory. At first sight a warped compactification geometry seems to produce a naturally flat inflaton potential, evading one wellknown difficulty of braneantibrane scenarios. Careful consideration of the closed ..."
Abstract

Cited by 82 (9 self)
 Add to MetaCart
(Show Context)
We investigate the embedding of brane inflation into stable compactifications of string theory. At first sight a warped compactification geometry seems to produce a naturally flat inflaton potential, evading one wellknown difficulty of braneantibrane scenarios. Careful consideration of the closed string moduli reveals a further obstacle: superpotential stabilization of the compactification volume typically modifies the inflaton potential and renders it too steep for inflation. We discuss the nongeneric conditions under which this problem does not arise. We conclude that brane inflation models can only work if restrictive assumptions about the method of volume stabilization, the warping of the internal space, and the source of inflationary energy are satisfied. We argue that this may not be a real problem, given the large range of available fluxes and background geometries in string theory.
Distributions of Nonsupersymmetric Flux Vacua
, 2004
"... We continue the study of the distribution of nonsupersymmetric flux vacua in IIb string theory compactified on CalabiYau manifolds, as in hepth/0404116. We show that the basic structure of this problem is that of finding eigenvectors of the matrix of second derivatives of the superpotential, and t ..."
Abstract

Cited by 77 (9 self)
 Add to MetaCart
We continue the study of the distribution of nonsupersymmetric flux vacua in IIb string theory compactified on CalabiYau manifolds, as in hepth/0404116. We show that the basic structure of this problem is that of finding eigenvectors of the matrix of second derivatives of the superpotential, and that many features of the results are determined by features of the generic ensemble of such matrices, the CI ensemble of Altland and Zirnbauer originating in mesoscopic physics. We study some simple examples in detail, exhibiting various factors which can favor low or high scale supersymmetry breaking.
An inflaton mass problem in string inflation from threshold corrections to volume stabilization
 LETT. B
, 2005
"... Inflationary models whose vacuum energy arises from a Dterm are believed not to suffer from the supergravity eta problem of Fterm inflation. That is, Dterm models have the desirable property that the inflaton mass can naturally remain much smaller than the Hubble scale. We observe that this advan ..."
Abstract

Cited by 15 (1 self)
 Add to MetaCart
(Show Context)
Inflationary models whose vacuum energy arises from a Dterm are believed not to suffer from the supergravity eta problem of Fterm inflation. That is, Dterm models have the desirable property that the inflaton mass can naturally remain much smaller than the Hubble scale. We observe that this advantage is lost in models based on string compactifications whose volume is stabilized by a nonperturbative superpotential: the Fterm energy associated with volume stabilization causes the eta problem to reappear. Moreover, any shift symmetries introduced to protect the inflaton mass will typically be lifted by threshold corrections to the volumestabilizing superpotential. Using threshold corrections computed by Berg, Haack, and Körs, we illustrate this point in the example of the D3D7 inflationary model, and conclude that inflation is possible, but only for finetuned values of the stabilized moduli. More generally, we conclude that inflationary models in stable string compactifications, even Dterm models with shift symmetries, will require a certain amount of finetuning to avoid this new contribution to the eta problem
Gaugino Condensates and Dterms from D7branes
, 2006
"... We investigate, at the microscopic level, the compatibility between Dterm potentials from worldvolume fluxes on D7branes and nonperturbative superpotentials arising from gaugino condensation on a different stack of D7branes. This is motivated by attempts to construct metastable de Sitter vacua ..."
Abstract

Cited by 15 (1 self)
 Add to MetaCart
We investigate, at the microscopic level, the compatibility between Dterm potentials from worldvolume fluxes on D7branes and nonperturbative superpotentials arising from gaugino condensation on a different stack of D7branes. This is motivated by attempts to construct metastable de Sitter vacua in type IIB string theory via Dterm uplifts. We find a condition under which the Kähler modulus, T, of a CalabiYau 4cycle gets charged under the anomalous U(1) on the branes with flux. If in addition this 4cycle is wrapped by a stack of D7branes on which gaugino condensation takes place, the question of U(1)gauge invariance of the (Tdependent) nonperturbative superpotential arises. In this case an index theorem guarantees that strings, stretching between the two stacks, yield additional charged chiral fields which also appear in the superpotential from gaugino condensation. We check that the charges work out to make this superpotential gauge invariant, and we argue that the mechanism survives the inclusion of higher curvature corrections to the D7brane action.
Comment on the FayetIliopoulos Term in Field Theory and Supergravity
, 2009
"... A careful analysis of the FayetIliopoulos (FI) model shows that its energy momentum tensor and supersymmetry current are not gauge invariant. Since the corresponding charges are gauge invariant, the model is consistent. However, our observation about the currents gives a new perspective on its rest ..."
Abstract

Cited by 13 (0 self)
 Add to MetaCart
A careful analysis of the FayetIliopoulos (FI) model shows that its energy momentum tensor and supersymmetry current are not gauge invariant. Since the corresponding charges are gauge invariant, the model is consistent. However, our observation about the currents gives a new perspective on its restrictive renormalization group flow and explains why FIterms never appear in dynamical supersymmetry breaking. This lack of gauge invariance is at the root of the complications of coupling the model to supergravity. We show that this is possible only if the full supergravity theory (including all higher derivative corrections) has an additional exact continuous global symmetry. A consistent quantum gravity theory cannot have such symmetries and hence FIterms cannot appear. Our results have consequences for various models of particle physics and cosmology.
Fterm uplifting and moduli stabilization consistent with Kähler invariance
, 2007
"... An important ingredient in the construction of phenomenologically viable superstring models is the uplifting of Antide Sitter supersymmetric critical points in the moduli sector to metastable Minkowski or de Sitter vacua with broken supersymmetry. In all cases described so far, uplifting results ..."
Abstract

Cited by 13 (2 self)
 Add to MetaCart
An important ingredient in the construction of phenomenologically viable superstring models is the uplifting of Antide Sitter supersymmetric critical points in the moduli sector to metastable Minkowski or de Sitter vacua with broken supersymmetry. In all cases described so far, uplifting results in a displacement of the potential minimum away from the critical point and, if the uplifting is large, can lead to the disappearance of the minimum altogether. We propose a variant of Fterm uplifting which exactly preserves supersymmetric critical points and shift symmetries at tree level. In spite of a direct coupling, the moduli do not contribute to supersymmetry breaking. We analyse the stability of the critical points in a toy onemodulus sector before and after uplifting, and find a simple stability condition depending solely on the amount of uplifting and not on the details of the uplifting sector. There is a region of parameter space, corresponding to the uplifting of local AdS maxima –or, more importantly, local minima of the Kähler function – where the critical points are stable for any amount of uplifting. On the other hand, uplifting to (nonsupersymmetric) Minkowski space is special in that all SUSY critical points, that is, for all possible compactifications, become stable or neutrally stable.
Stable de Sitter Vacua in 4 Dimensional Supergravity Originating from 5 Dimensions
, 809
"... The five dimensional stable de Sitter ground states in N = 2 supergravity obtained by gauging SO(1,1) symmetry of the real symmetric scalar manifold (in particular a generic Jordan family manifold of the vector multiplets) simultaneously with a subgroup Rs of the Rsymmetry group descend to four dim ..."
Abstract

Cited by 12 (0 self)
 Add to MetaCart
(Show Context)
The five dimensional stable de Sitter ground states in N = 2 supergravity obtained by gauging SO(1,1) symmetry of the real symmetric scalar manifold (in particular a generic Jordan family manifold of the vector multiplets) simultaneously with a subgroup Rs of the Rsymmetry group descend to four dimensional de Sitter ground states under certain conditions. First, the holomorphic section in four dimensions has to be chosen carefully by using the symplectic freedom in four dimensions; and second, a group contraction is necessary to bring the potential into a desired form. Under these conditions, stable de Sitter vacua can be obtained in dimensionally reduced theories (from 5D to 4D) if the semidirect product of SO(1,1) with R (1,1) together with a simultaneous Rs is gauged. We review the stable de Sitter vacua in four dimensions found in earlier literature for N = 2 YangMills Einstein supergravity with SO(2,1) ×Rs gauge group in a symplectic basis that comes naturally after dimensional reduction. Although this particular gauge group does not descend directly from five dimensions, we show that, its contraction does. Hence, two different theories overlap in certain limits. Examples of stable de Sitter vacua are given for
Dterms and Dstrings in open string models
 JHEP 0410 (2004) 056 [arXiv:hepth/0409284
"... We study the FayetIliopoulos (FI) Dterms on Dbranes in type II CalabiYau backgrounds. We provide a simple worldsheet proof of the fact that, at tree level, these terms only couple to scalars in closed string hypermultiplets. At the oneloop level, the Dterms get corrections only if the gauge gr ..."
Abstract

Cited by 12 (1 self)
 Add to MetaCart
We study the FayetIliopoulos (FI) Dterms on Dbranes in type II CalabiYau backgrounds. We provide a simple worldsheet proof of the fact that, at tree level, these terms only couple to scalars in closed string hypermultiplets. At the oneloop level, the Dterms get corrections only if the gauge group has an anomalous spectrum, with the anomaly cancelled by a GreenSchwarz mechanism. We study the local type IIA model of D6branes at SU(3) angles and show that, as in field theory, the oneloop correction suffers from a quadratic divergence in the open string channel. By studying the closed string channel, we show that this divergence is related to a closed string tadpole, and is cancelled when the tadpole is cancelled. Next, we study the cosmic strings that arise in the supersymmetric phases of these systems in light of recent work of Dvali et. al. In the type IIA intersecting D6brane examples, we identify the Dterm strings as D4branes ending on the D6branes. Finally, we use N = 1 dualities to relate these results to previous work on the FI Dterm of heterotic strings. September