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Hierarchies from Fluxes in String Compactifications
, 2002
"... Warped compactifications with significant warping provide one of the few known mechanisms for naturally generating large hierarchies of physical scales. We demonstrate that this mechanism is realizable in string theory, and give examples involving orientifold compactifications of IIB string theory a ..."
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Cited by 715 (33 self)
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Warped compactifications with significant warping provide one of the few known mechanisms for naturally generating large hierarchies of physical scales. We demonstrate that this mechanism is realizable in string theory, and give examples involving orientifold compactifications of IIB string theory and Ftheory compactifications on CalabiYau fourfolds. In each case, the hierarchy of scales is fixed by a choice of RR and NS fluxes in the compact manifold. Our solutions involve compactifications of the KlebanovStrassler gravity dual to a confining N = 1 supersymmetric gauge theory, and the hierarchy reflects the small scale of chiral symmetry breaking in the dual gauge theory.
The Confrontation between General Relativity and Experiment
 Living Rev. Relativity 9
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An alternative to compactification
 Phy. Rev. Lett
, 1999
"... Conventional wisdom states that Newton’s force law implies only four noncompact dimensions. We demonstrate that this is not necessarily true in the presence of a nonfactorizable background geometry. The specific example we study is a single 3brane embedded in five dimensions. We show that even wi ..."
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Cited by 186 (1 self)
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Conventional wisdom states that Newton’s force law implies only four noncompact dimensions. We demonstrate that this is not necessarily true in the presence of a nonfactorizable background geometry. The specific example we study is a single 3brane embedded in five dimensions. We show that even without a gap in the KaluzaKlein spectrum, fourdimensional There exists “lore ” that convinces us that we live in four noncompact dimensions. Certainly Standard Model matter cannot propagate a large distance in extra dimensions without conflict with observations. As has recently been emphasized, this can be avoided if the Standard Model is confined to a (3 + 1)dimensional subspace, or “3brane”, in the higher dimensions
Brane/Flux Annihilation and the String Dual of a NonSupersymmetric Field Theory
, 2006
"... We consider the dynamics of p antiD3 branes inside the KlebanovStrassler geometry, the deformed conifold with M units of RR 3form flux around the S 3. We find that for p << M the system relaxes to a nonsupersymmetric NS 5brane “giant graviton ” configuration, which is classically stable, b ..."
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Cited by 170 (18 self)
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We consider the dynamics of p antiD3 branes inside the KlebanovStrassler geometry, the deformed conifold with M units of RR 3form flux around the S 3. We find that for p << M the system relaxes to a nonsupersymmetric NS 5brane “giant graviton ” configuration, which is classically stable, but quantum mechanically can tunnel to a nearby supersymmetric vacuum with M −p D3 branes. This decay mode is exponentially suppressed and proceeds via the nucleation of an NS 5brane bubble wall. We propose a dual field theory interpretation of the decay as the transition between a nonsupersymmetric “baryonic” branch and a supersymmetric “mesonic” branch of the corresponding SU(2M − p) × SU(M − p) low energy gauge theory. The NS 5brane tunneling process also provides a simple visualization of the The search for calculable and nontrivial nonsupersymmetric string vacua remains a problem of basic interest in string theory. In the context of AdS/CFT duality [1], this is related to the construction of gravitational “antiholographic” descriptions for nonsupersymmetric 4d quantum gauge theories. Here, we describe the construction of a simple nonsupersymmetric
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
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.
The holographic principle
 Rev. Mod. Phys
, 2002
"... There is strong evidence that the area of any surface limits the information content of adjacent spacetime regions, at 1.4 ×10 69 bits per square meter. We review the developments that have led to the recognition of this entropy bound, placing special emphasis on the quantum properties of black hole ..."
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Cited by 132 (9 self)
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There is strong evidence that the area of any surface limits the information content of adjacent spacetime regions, at 1.4 ×10 69 bits per square meter. We review the developments that have led to the recognition of this entropy bound, placing special emphasis on the quantum properties of black holes. The construction of lightsheets, which associate relevant spacetime regions to any
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
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.
Spectral Dimension of the Universe in Quantum Gravity at a Lifshitz Point
, 2009
"... We extend the definition of “spectral dimension ” (usually defined for fractal and lattice geometries) to theories on smooth spacetimes with anisotropic scaling. We show that in quantum gravity dominated by a Lifshitz point with dynamical critical exponent z in D+1 spacetime dimensions, the spectr ..."
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Cited by 81 (0 self)
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We extend the definition of “spectral dimension ” (usually defined for fractal and lattice geometries) to theories on smooth spacetimes with anisotropic scaling. We show that in quantum gravity dominated by a Lifshitz point with dynamical critical exponent z in D+1 spacetime dimensions, the spectral dimension of spacetime is equal to ds = 1 + D z. In the case of gravity in 3 + 1 dimensions presented in arXiv:0901.3775, which is dominated by z = 3 in the UV and flows to z = 1 in the IR, the spectral dimension of spacetime flows from ds = 4 at large scales, to ds = 2 at short distances. Remarkably, this is the qualitative behavior of ds found numerically by Ambjørn, Jurkiewicz and Loll in their causal dynamical