The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Kenta Suzuki - One of the best experts on this subject based on the ideXlab platform.
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bi local holography in the syk model perturbations
arXiv: High Energy Physics - Theory, 2016Co-Authors: Antal Jevicki, Kenta SuzukiAbstract:We continue the study of the Sachdev-Ye-Kitaev model in the Large $N$ limit. Following our formulation in terms of bi-local collective fields with dynamical Reparametrization symmetry, we perform perturbative calculations around the conformal IR point.
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bi local holography in the syk model perturbations
Journal of High Energy Physics, 2016Co-Authors: Antal Jevicki, Kenta SuzukiAbstract:We continue the study of the Sachdev-Ye-Kitaev model in the Large N limit. Following our formulation in terms of bi-local collective fields with dynamical Reparametrization symmetry, we perform perturbative calculations around the conformal IR point. These are based on an e expansion which allows for analytical evaluation of correlators and finite temperature quantities.
Manuel Vielma - One of the best experts on this subject based on the ideXlab platform.
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eigenstate thermalisation in the conformal sachdev ye kitaev model an analytic approach
Journal of High Energy Physics, 2019Co-Authors: P K Nayak, Julian Sonner, Manuel VielmaAbstract:The Sachdev-Ye-Kitaev (SYK) model provides an uncommon example of a chaotic theory that can be analysed analytically. In the deep infrared limit, the original model has an emergent conformal (reparametrisation) symmetry that is broken both spontaneously and explicitly. The explicit breaking of this symmetry comes about due to pseudo-Nambu-Goldstone modes that are not exact zero-modes of the model. In this paper, we study a version of the model which preserves the reparametrisation symmetry at all length scales. We study the heavy-light correlation functions of the operators in the conformal spectrum of the theory. The three point functions of such operators allow us to demonstrate that matrix elements of primaries O n of the CFT1 take the form postulated by the Eigenstate Thermalisation Hypothesis. We also discuss the implications of these results for the states in AdS2 gravity dual.
Alan S. Willsky - One of the best experts on this subject based on the ideXlab platform.
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tree based reparameterization framework for analysis of sum product and related algorithms
IEEE Transactions on Information Theory, 2003Co-Authors: Martin J. Wainwright, Tommi S. Jaakkola, Alan S. WillskyAbstract:We present a tree-based reparameterization (TRP) framework that provides a new conceptual view of a large class of algorithms for computing approximate marginals in graphs with cycles. This class includes the belief propagation (BP) or sum-product algorithm as well as variations and extensions of BP. Algorithms in this class can be formulated as a sequence of reparameterization updates, each of which entails refactorizing a portion of the distribution corresponding to an acyclic subgraph (i.e., a tree, or more generally, a hypertree). The ultimate goal is to obtain an alternative but equivalent factorization using functions that represent (exact or approximate) marginal distributions on cliques of the graph. Our framework highlights an important property of the sum-product algorithm and the larger class of reparameterization algorithms: the original distribution on the graph with cycles is not changed. The perspective of tree-based updates gives rise to a simple and intuitive characterization of the fixed points in terms of tree consistency. We develop interpretations of these results in terms of information geometry. The invariance of the distribution, in conjunction with the fixed-point characterization, enables us to derive an exact expression for the difference between the true marginals on an arbitrary graph with cycles, and the approximations provided by belief propagation. More broadly, our analysis applies to any algorithm that minimizes the Bethe free energy. We also develop bounds on the approximation error, which illuminate the conditions that govern their accuracy. Finally, we show how the reparameterization perspective extends naturally to generalizations of BP (e.g., Kikuchi (1951) approximations and variants) via the notion of hypertree reparameterization.
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tree based reparameterization for approximate inference on loopy graphs
Neural Information Processing Systems, 2001Co-Authors: Martin J. Wainwright, Tommi S. Jaakkola, Alan S. WillskyAbstract:We develop a tree-based reparameterization framework that provides a new conceptual view of a large class of iterative algorithms for computing approximate marginals in graphs with cycles. It includes belief propagation (BP), which can be reformulated as a very local form of reparameterization. More generally, we consider algorithms that perform exact computations over spanning trees of the full graph. On the practical side, we find that such tree reparameterization (TRP) algorithms have convergence properties superior to BP. The reparameterization perspective also provides a number of theoretical insights into approximate inference, including a new characterization of fixed points; and an invariance intrinsic to TRP/BP. These two properties enable us to analyze and bound the error between the TRP/BP approximations and the actual marginals. While our results arise naturally from the TRP perspective, most of them apply in an algorithm-independent manner to any local minimum of the Bethe free energy. Our results also have natural extensions to more structured approximations [e.g., 1, 2].
Antal Jevicki - One of the best experts on this subject based on the ideXlab platform.
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bi local holography in the syk model perturbations
arXiv: High Energy Physics - Theory, 2016Co-Authors: Antal Jevicki, Kenta SuzukiAbstract:We continue the study of the Sachdev-Ye-Kitaev model in the Large $N$ limit. Following our formulation in terms of bi-local collective fields with dynamical Reparametrization symmetry, we perform perturbative calculations around the conformal IR point.
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bi local holography in the syk model perturbations
Journal of High Energy Physics, 2016Co-Authors: Antal Jevicki, Kenta SuzukiAbstract:We continue the study of the Sachdev-Ye-Kitaev model in the Large N limit. Following our formulation in terms of bi-local collective fields with dynamical Reparametrization symmetry, we perform perturbative calculations around the conformal IR point. These are based on an e expansion which allows for analytical evaluation of correlators and finite temperature quantities.
Richard Kerner - One of the best experts on this subject based on the ideXlab platform.
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time Reparametrization invariance and hamilton jacobi approach to the cosmological σ model
Protein Science, 2014Co-Authors: J W Van Holten, Richard KernerAbstract:The construction of physical models with local time-Reparametrization invariance is reviewed. Negative-energy contributions to the hamiltonian are shown to be crucial for the realization of this Reparametrization symmetry. The covariant formulation of the dynamics is used to develop a time and gauge invariant Hamilton-Jacobi theory. This formalism is applied to solve for the cosmology of a homogeneous universe of the Friedmann-Lemaitre-Robertson-Walker type. After a discussion of empty universes, the FLRW theory is extended with homogeneous scalar elds generically described by a -model on some scalar manifold. An explicit gauge-invariant solution is constructed for the non-linear O(N)-models.
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time Reparametrization invariance and hamilton jacobi approach to the cosmological sigma model
arXiv: High Energy Physics - Theory, 2013Co-Authors: J W Van Holten, Richard KernerAbstract:The construction of physical models with local time-Reparametrization invariance is reviewed. Negative-energy contributions to the hamiltonian are shown to be crucial for the realization of this Reparametrization symmetry. The covariant formulation of the dynamics is used to develop a time and gauge invariant Hamilton-Jacobi theory. This formalism is applied to solve for the cosmology of a homogeneous universe of the Friedmann-Lemaitre-Robertson-Walker type. After a discussion of empty universes, the FLRW theory is extended with homogeneous scalar fields generically described by a $\sg$-model on some scalar manifold. An explicit gauge-invariant solution is constructed for the non-linear O(N)-models.
