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291
Large N field theories, string theory and gravity
, 2001
"... We review the holographic correspondence between field theories and string/M theory, focusing on the relation between compactifications of string/M theory on Antide Sitter spaces and conformal field theories. We review the background for this correspondence and discuss its motivations and the evide ..."
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Cited by 1443 (45 self)
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We review the holographic correspondence between field theories and string/M theory, focusing on the relation between compactifications of string/M theory on Antide Sitter spaces and conformal field theories. We review the background for this correspondence and discuss its motivations and the evidence for its correctness. We describe the main results that have been derived from the correspondence in the regime that the field theory is approximated by classical or semiclassical gravity. We focus on the case of the N = 4 supersymmetric gauge theory in four dimensions, but we discuss also field theories in other dimensions, conformal and nonconformal, with or without supersymmetry, and in particular the relation to QCD. We also discuss some implications for black hole physics.
The dS/CFT correspondence
 JHEP
, 2001
"... A holographic duality is proposed relating quantum gravity on dSD (Ddimensional de Sitter space) to conformal field theory on a single SD−1 ((D1)sphere), in which bulk de Sitter correlators with points on the boundary are related to CFT correlators on the sphere, and points on I + (the future bou ..."
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Cited by 196 (7 self)
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A holographic duality is proposed relating quantum gravity on dSD (Ddimensional de Sitter space) to conformal field theory on a single SD−1 ((D1)sphere), in which bulk de Sitter correlators with points on the boundary are related to CFT correlators on the sphere, and points on I + (the future boundary of dSD) are mapped to the antipodal points on SD−1 relative to those on I −. For the case of dS3, which is analyzed in some detail, the central charge of the CFT2 is computed in an analysis of the asymptotic symmetry group at I ±. This dS/CFT proposal is supported by the computation of correlation functions of a massive scalar field. In general the dual CFT may be nonunitary and (if for example there are sufficently massive stable scalars) contain complex conformal weights. We also consider the physical region O − of dS3 corresponding to the causal past of a timelike observer, whose holographic dual lives on a plane rather than a sphere. O − can be foliated by asymptotically flat spacelike slices. Time evolution along these slices is generated by
Exploring improved holographic theories for QCD
 Part I”, [ArXiv:0707.1324
"... Abstract: This paper is a continuation of ArXiv:0707.1324 where improved holographic theories for QCD were set up and explored. Here, the IR confining geometries are classified and analyzed. They all end in a “good ” (repulsive) singularity in the IR. The glueball spectra are gaped and discrete, and ..."
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Cited by 115 (15 self)
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Abstract: This paper is a continuation of ArXiv:0707.1324 where improved holographic theories for QCD were set up and explored. Here, the IR confining geometries are classified and analyzed. They all end in a “good ” (repulsive) singularity in the IR. The glueball spectra are gaped and discrete, and they favorably compare to the lattice data. Quite generally, confinement and discrete spectra imply each other. Asymptotically linear glueball masses can also be achieved. Asymptotic mass ratios of various glueballs with different spin also turn out to be universal. Mesons dynamics is implemented via space filling D4 − ¯ D4 brane pairs. The associated tachyon dynamics is analyzed and chiral symmetry breaking is shown. The dynamics of the RR axion is analyzed, and the nonperturbative running of the QCD θangle is obtained. It is shown to always vanish in the IR.
Curvature singularities: The good, the bad, and the naked
 Adv. Theor. Math. Phys
, 2002
"... Necessary conditions are proposed for the admissibility of singular classical solutions with 3 + 1dimensional Poincaré invariance to fivedimensional gravity coupled to scalars. Finite temperature considerations and examples from AdS/CFT support the conjecture that the scalar potential must remain ..."
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Cited by 99 (7 self)
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Necessary conditions are proposed for the admissibility of singular classical solutions with 3 + 1dimensional Poincaré invariance to fivedimensional gravity coupled to scalars. Finite temperature considerations and examples from AdS/CFT support the conjecture that the scalar potential must remain bounded above for a solution to be physical. Having imposed some restrictions on naked singularities allows us to comment on a recent proposal for solving the cosmological constant problem. In AdS/CFT [1, 2, 3] (see [4] for a review), bulk geometries which are only asymptotically AdS5 near the timelike boundary are dual to relevant deformations of the CFT or to nonconformal vacua. Far from the timelike boundary, various singularities might arise. There must be some restrictions on the type of singularity which is allowed: for
The cosmological constant from the viewpoint of string theory
, 2000
"... The mystery of the cosmological constant is probably the most pressing obstacle to significantly improving the models of elementary particle physics derived from string theory. The problem arises because in the standard framework of low energy physics, there appears to be no natural explanation for ..."
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Cited by 89 (0 self)
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The mystery of the cosmological constant is probably the most pressing obstacle to significantly improving the models of elementary particle physics derived from string theory. The problem arises because in the standard framework of low energy physics, there appears to be no natural explanation for vanishing or extreme smallness of the vacuum energy, while on the other hand it is very difficult to modify this framework in a sensible way. In seeking to resolve this problem, one naturally wonders if the real world can somehow be interpreted in terms of a vacuum state with unbroken supersymmetry.
Compact and noncompact gauged maximal supergravities in three dimensions
 JHEP 0104, 022 (2001). HEPTH/0103032. 29 NICOLAI, H., SAMTLEBEN, H.: N = 8 MATTER COUPLED ADS3
, 2001
"... We present the maximally supersymmetric threedimensional gauged supergravities. Owing to the special properties of three dimensions — especially the onshell duality between vector and scalar fields, and the purely topological character of (super)gravity — they exhibit an even richer structure than ..."
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Cited by 70 (18 self)
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We present the maximally supersymmetric threedimensional gauged supergravities. Owing to the special properties of three dimensions — especially the onshell duality between vector and scalar fields, and the purely topological character of (super)gravity — they exhibit an even richer structure than the gauged supergravities in higher dimensions. The allowed gauge groups are subgroups of the global E 8(8) symmetry of ungauged N = 16 supergravity. They include the regular series SO(p, 8 −p) ×SO(p, 8 −p) for all p = 0, 1,..., 4, the group E 8(8) itself, as well as various noncompact forms of the exceptional groups E7, E6 and F4 × G2. We show that all these theories admit maximally supersymmetric ground states, and determine their background isometries, which are superextensions of the antide Sitter group SO(2, 2). The very existence of these theories is argued to point to a new supergravity beyond the standard D=11 supergravity.