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167
Scalar speed limits and cosmology: Acceleration from D cceleration
 Phys. Rev. D70 (2004) 103505, hepth/0310221
"... Causality on the gravity side of the AdS/CFT correspondence restricts motion on the moduli space of the N = 4 super Yang Mills theory by imposing a speed limit on how fast the scalar field may roll. This effect can be traced to higher derivative operators arising from integrating out light degrees o ..."
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Cited by 166 (11 self)
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Causality on the gravity side of the AdS/CFT correspondence restricts motion on the moduli space of the N = 4 super Yang Mills theory by imposing a speed limit on how fast the scalar field may roll. This effect can be traced to higher derivative operators arising from integrating out light degrees of freedom near the origin. In the strong coupling limit of the theory, the dynamics is well approximated by the DiracBornInfeld Lagrangian for a probe D3brane moving toward the horizon of the AdS Poincare patch, combined with an estimate of the (ultimately suppressed) rate of particle and string production in the system. We analyze the motion of a rolling scalar field explicitly in the strong coupling regime of the field theory, and extend the analysis to cosmological systems obtained by coupling this type of field theory to four dimensional gravity. This leads to a mechanism for slow roll inflation for a massive scalar at subPlanckian VEV without need for a flat potential (realizing a version of kinflation in a microphysical framework). It also leads to a variety of novel FRW cosmologies, some of which
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 ..."
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Cited by 165 (16 self)
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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
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
Moduli Stabilization from Fluxes in a Simple IIB Orientifold
, 2002
"... We study novel type IIB compactifications on the T 6 /Z2 orientifold. This geometry arises in the Tdual description of Type I theory on T 6, and one normally introduces 16 spacefilling D3branes to cancel the RR tadpoles. Here, we cancel the RR tadpoles either partially or fully by turning on thre ..."
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Cited by 149 (10 self)
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We study novel type IIB compactifications on the T 6 /Z2 orientifold. This geometry arises in the Tdual description of Type I theory on T 6, and one normally introduces 16 spacefilling D3branes to cancel the RR tadpoles. Here, we cancel the RR tadpoles either partially or fully by turning on threeform flux in the compact geometry. The resulting (super)potential for moduli is calculable. We demonstrate that one can find many examples of N = 1 supersymmetric vacua with greatly reduced numbers of moduli in this system. A few examples with N> 1 supersymmetry or complete supersymmetry breaking are also discussed.
Fixing all moduli in a simple Ftheory compactification,” [arXiv:hepth/0503124
"... We discuss a simple example of an Ftheory compactification on a CalabiYau fourfold where background fluxes, nonperturbative effects from Euclidean D3 instantons and gauge dynamics on D7 branes allow us to fix all closed and open string moduli. We explicitly check that the known higher order correc ..."
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Cited by 91 (8 self)
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We discuss a simple example of an Ftheory compactification on a CalabiYau fourfold where background fluxes, nonperturbative effects from Euclidean D3 instantons and gauge dynamics on D7 branes allow us to fix all closed and open string moduli. We explicitly check that the known higher order corrections to the potential, which we neglect in our leading approximation, only shift the results by a small amount. In our exploration of the model, we encounter interesting new phenomena, including examples of transitions where D7 branes absorb O3 planes, while changing topology to preserve the net D3 charge.
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 ..."
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Cited by 82 (9 self)
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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.
Dynamics of warped compactifications and the shape of the warped landscape
, 2005
"... The dynamics of warped/flux compactifications is studied, including warping effects, providing a firmer footing for investigation of the “landscape.” We present a general formula for the fourdimensional potential of warped compactifications in terms of tendimensional quantities. This allows a syste ..."
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Cited by 77 (2 self)
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The dynamics of warped/flux compactifications is studied, including warping effects, providing a firmer footing for investigation of the “landscape.” We present a general formula for the fourdimensional potential of warped compactifications in terms of tendimensional quantities. This allows a systematic investigation of modulifixing effects and potentials for mobile branes. We provide a necessary criterion, “slopedominance, ” for evading “nogo ” results for de Sitter vacua. We outline the tendimensional derivation of the nonperturbative effects that should accomplish this in KKLT examples, and outline a systematic discussion of their corrections. We show that potentials for mobile branes receive generic contributions inhibiting slowroll inflation. We give a linearized analysis of general scalar perturbations of warped IIB compactifications, revealing new features for both time independent and dependent moduli, and new aspects of the kinetic part of the fourdimensional effective action. The universal Kahler modulus is found not to be a simple scaling of the internal metric, and a prescription is given for defining holomorphic Kahler moduli, including warping effects. In the presence of mobile branes, this
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 ..."
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Cited by 77 (9 self)
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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.
Direct mediation of metastable supersymmetry breaking,” hepph/0612139
"... The supersymmetric SU(NC) YangMills theory coupled to NF matter fields in the fundamental representation has metastable vacua with broken supersymmetry when NC < NF < 3 2 NC. By gauging the flavor symmetry, this model can be coupled directly to the standard model. We show that it is possible ..."
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Cited by 69 (10 self)
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The supersymmetric SU(NC) YangMills theory coupled to NF matter fields in the fundamental representation has metastable vacua with broken supersymmetry when NC < NF < 3 2 NC. By gauging the flavor symmetry, this model can be coupled directly to the standard model. We show that it is possible to make a slight deformation to the model so that gaugino masses are generated and the Landau pole problem can be avoided. The deformed model has simple realizations on intersecting branes in string theory, where various Although there is no clear evidence yet, it is plausible that softly broken N = 1 supersymmetry is realized in nature. Not only because it is a symmetry possessed by string theory, there are many phenomenologically attractive features in supersymmetric models, such as cancellation of quadratic divergences and unification of the gauge coupling constants [1, 2, 3].
The scaling of the noscale potential and de Sitter model building
"... We propose a variant of the KKLT (A)dS flux vacuum construction which does not require an antibrane to source the volume modulus. The strategy is to find nonzero local minima of the noscale potential in the complex structure and dilaton directions in moduli space. The corresponding noscale potenti ..."
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Cited by 61 (3 self)
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We propose a variant of the KKLT (A)dS flux vacuum construction which does not require an antibrane to source the volume modulus. The strategy is to find nonzero local minima of the noscale potential in the complex structure and dilaton directions in moduli space. The corresponding noscale potential expanded about this point sources the volume modulus in the same way as does the antibrane of the KKLT construction. We exhibit explicit examples of such nonzero local minima of the noscale potential in a simple toroidal orientifold model.