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21
On the Newtonian limit of emergent NC gravity and longdistance corrections
, 2009
"... We show how Newtonian gravity emerges on 4dimensional noncommutative spacetime branes in YangMills matrix models. Large matter clusters such as galaxies are embedded in largescale harmonic deformations of the spacetime brane, which screen gravity for long distances. On shorter scales, the local ..."
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Cited by 10 (9 self)
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We show how Newtonian gravity emerges on 4dimensional noncommutative spacetime branes in YangMills matrix models. Large matter clusters such as galaxies are embedded in largescale harmonic deformations of the spacetime brane, which screen gravity for long distances. On shorter scales, the local matter distribution reproduces Newtonian gravity via local deformations of the brane and its metric. The harmonic “gravity bag ” acts as a halo with effective positive energy density. This leads in particular to a significant enhancement of the orbital velocities around galaxies at large distances compared with the Newtonian case, before dropping to zero as the geometry merges with a Milnelike cosmology. Besides these “harmonic ” solutions, there is another class of solutions which is more similar to Einstein gravity. Thus the IKKT model provides an accessible candidate for a quantum theory of gravity.
Fermions and noncommutative emergent gravity. II. Curved branes in extra dimensions
 J. High Energy Phys
"... branes in extra dimensions ..."
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Gauge Theories on Deformed Spaces
 SYMMETRY, INTEGRABILITY AND GEOMETRY: METHODS AND APPLICATIONS
, 2010
"... The aim of this review is to present an overview over available models and approaches to noncommutative gauge theory. Our main focus thereby is on gauge models formulated on flat Groenewold–Moyal spaces and renormalizability, but we will also review other deformations and try to point out common fe ..."
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The aim of this review is to present an overview over available models and approaches to noncommutative gauge theory. Our main focus thereby is on gauge models formulated on flat Groenewold–Moyal spaces and renormalizability, but we will also review other deformations and try to point out common features. This review will by no means be complete and cover all approaches, it rather reflects a highly biased selection.
UWTHPh200907 On the Newtonian limit of emergent NC gravity and longdistance corrections
, 909
"... We show how Newtonian gravity emerges on 4dimensional noncommutative spacetime branes in YangMills matrix models. Large matter clusters such as galaxies are embedded in largescale harmonic deformations of the spacetime brane, which screen gravity for long distances. On shorter scales, the local ..."
Abstract
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We show how Newtonian gravity emerges on 4dimensional noncommutative spacetime branes in YangMills matrix models. Large matter clusters such as galaxies are embedded in largescale harmonic deformations of the spacetime brane, which screen gravity for long distances. On shorter scales, the local matter distribution reproduces Newtonian gravity via local deformations of the brane and its metric. The harmonic “gravity bag ” acts as a halo with effective positive energy density. This leads in particular to a significant enhancement of the orbital velocities around galaxies at large distances compared with the Newtonian case, before dropping to zero as the geometry merges with a Milnelike cosmology. Besides these “harmonic ” solutions, there is another class of solutions which is more similar to Einstein gravity. Thus the IKKT model provides an accessible candidate for a quantum theory of gravity. 1
Matrix Models, Emergent Gravity, and Gauge Theory
, 903
"... Matrix models of YangMills type induce an effective gravity theory on 4dimensional branes, which are considered as models for dynamical spacetime. We review recent progress in the understanding of this emergent gravity. The metric is not fundamental but arises effectively in the semiclassical li ..."
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Matrix models of YangMills type induce an effective gravity theory on 4dimensional branes, which are considered as models for dynamical spacetime. We review recent progress in the understanding of this emergent gravity. The metric is not fundamental but arises effectively in the semiclassical limit, along with nonabelian gauge fields. This leads to a mechanism for protecting certain geometries from corrections due to the vacuum energy. 1 Background and motivation Quantum field theory and general relativity (GR) provide the basis of our present understanding of fundamental matter and interactions. In spite of the success of these two theories, there is up to now no satisfactory way to reconcile them in a consistent quantum theory. In particular, quantum mechanics combined with GR strongly suggests a “foamlike ” or quantum structure at the Planck scale 10 −33 cm, where quantum fluctuations of spacetime are expected to be important. While some kind of quantum structure of spacetime indeed arises e.g. in string theory, a satisfactory understanding is still missing. The cosmological constant problem should be seen in the same context: the observed tiny (or zero) value of the cosmological constant is in striking contradiction with quantum mechanical expectations, which are off by a factor of order 10 120. Reconciling quantum mechanics with gravity is therefore of utmost importance in theoretical physics. In view of these problems, it is natural to consider noncommutative (NC) or quantum spaces as models for spacetime. For fixed backgrounds, considerable work has been done in this context, leading to NC field theory [4]. Recently, it was understood that gravity emerges naturally from NC gauge theory, without having to introduce an explicit dynamical metric. Earlier forms of this idea [5,6] can be cast in concise form for matrix models of YangMills type [8], which describe dynamical quantum spaces. We discuss basic results of this approach. The IKKT model [10] is singled out as a prime candidate for a quantum theory of spacetime and matter. 2 The quantization of Poisson
Matrix Models, Emergent Gravity, and Gauge Theory
, 903
"... Matrix models of YangMills type induce an effective gravity theory on 4dimensional branes, which are considered as models for dynamical spacetime. We review recent progress in the understanding of this emergent gravity. The metric is not fundamental but arises effectively in the semiclassical li ..."
Abstract
 Add to MetaCart
(Show Context)
Matrix models of YangMills type induce an effective gravity theory on 4dimensional branes, which are considered as models for dynamical spacetime. We review recent progress in the understanding of this emergent gravity. The metric is not fundamental but arises effectively in the semiclassical limit, along with nonabelian gauge fields. This leads to a mechanism for protecting certain geometries from corrections due to the vacuum energy. 1 Background and motivation Quantum field theory and general relativity (GR) provide the basis of our present understanding of fundamental matter and interactions. In spite of the success of these two theories, there is up to now no satisfactory way to reconcile them in a consistent quantum theory. In particular, quantum mechanics combined with GR strongly suggests a “foamlike ” or quantum structure at the Planck scale 10 −33 cm, where quantum fluctuations of spacetime are expected to be important. While some kind of quantum structure of spacetime indeed arises e.g. in string theory, a satisfactory understanding is still missing. The cosmological constant problem should be seen in the same context: the observed tiny (or zero) value of the cosmological constant is in striking contradiction with quantum mechanical expectations, which are off by a factor of order 10 120. Reconciling quantum mechanics with gravity is therefore of utmost importance in theoretical physics. In view of these problems, it is natural to consider noncommutative (NC) or quantum spaces as models for spacetime. For fixed backgrounds, considerable work has been done in this context, leading to NC field theory [4]. Recently, it was understood that gravity emerges naturally from NC gauge theory, without having to introduce an explicit dynamical metric. Earlier forms of this idea [5,6] can be cast in concise form for matrix models of YangMills type [8], which describe dynamical quantum spaces. We discuss basic results of this approach. The IKKT model [10] is singled out as a prime candidate for a quantum theory of spacetime and matter. 2 The quantization of Poisson