Triangle Seminars
Wednesday, 6 Dec 2017
Holographic Phonons
Matteo Baggioli
(University of Crete)
Abstract:
We discuss the presence of phonons and
the interplay between spontaneous and explicit breaking
of translations in the context of holography.
Using two different bottom-up models we show the existence of
transverse and longitudinal phonons, whose properties are in
perfect agreement with elastic theory and hydrodynamics.
We focus our attention on the elastic and transport features
of the dual QFT also in the presence of a small explicit breaking.
We conclude speculating about the possibility of having
gravitational duals for strongly coupled viscoelastic materials.
We discuss the presence of phonons and
the interplay between spontaneous and explicit breaking
of translations in the context of holography.
Using two different bottom-up models we show the existence of
transverse and longitudinal phonons, whose properties are in
perfect agreement with elastic theory and hydrodynamics.
We focus our attention on the elastic and transport features
of the dual QFT also in the presence of a small explicit breaking.
We conclude speculating about the possibility of having
gravitational duals for strongly coupled viscoelastic materials.
Posted by: IC
Handling Handles: Nonplanar Integrability
📍 London
Joao Caetano
(ENS, Paris)
Abstract:
TRIANGULAR SEMINAR: We propose an integrability setup for the computation of correlation functions of gauge-invariant operators at any value of the 't Hooft coupling and at any order in the large Nc 't Hooft expansion in N = 4 SYM theory. In this multi-step proposal, one polygonizes the string worldsheet in all possible ways, hexagonalizes all resulting polygons, and sprinkles mirror particles over all hexagon junctions to obtain the full correlator. We test our integrability-based conjecture against a non-planar four-point correlator of large half-BPS operators at one and two loops.
TRIANGULAR SEMINAR: We propose an integrability setup for the computation of correlation functions of gauge-invariant operators at any value of the 't Hooft coupling and at any order in the large Nc 't Hooft expansion in N = 4 SYM theory. In this multi-step proposal, one polygonizes the string worldsheet in all possible ways, hexagonalizes all resulting polygons, and sprinkles mirror particles over all hexagon junctions to obtain the full correlator. We test our integrability-based conjecture against a non-planar four-point correlator of large half-BPS operators at one and two loops.
Posted by: KCL
Phases of Matrix Quantum Mechanics and Quantum Gravitational Collapse from the new Large D Limit
📍 London
Frank Ferrari
(Universite Libre de Bruxelles, Intl. Solvay Inst., IBS)
Abstract:
TRIANGULAR SEMINAR:
New techniques of large N and large D allow to study analytically planar matrix quantum mechanics at strong coupling in a reliable way. Using these techniques, we found a remarkable phase transition in these systems, which is very naturally interpreted as a quantum version of the phenomenon of black hole formation in a gravitational collapse.
<br>
Based on 1701.01171, 1707.03431, 1709.07366, 1710.07263 and work in progress.
TRIANGULAR SEMINAR:
New techniques of large N and large D allow to study analytically planar matrix quantum mechanics at strong coupling in a reliable way. Using these techniques, we found a remarkable phase transition in these systems, which is very naturally interpreted as a quantum version of the phenomenon of black hole formation in a gravitational collapse.
<br>
Based on 1701.01171, 1707.03431, 1709.07366, 1710.07263 and work in progress.
Posted by: KCL
Friday, 8 Dec 2017
Graduate Mini-course: Holographic combinatorics : 2d Yang Mills theory to tensor models via AdS/CFT
Sanjaye Ramgoolam
(QMUL)
Abstract:
These lectures will be focused on aspects of combinatorics relevant to gauge-string duality (holography).
The physical theories we will discuss include two dimensional Yang Mills
theory, four-dimensional N=4 super Yang Mills
theory with U(N) gauge group, Matrix and tensor models.
The key mathematical concepts include : Schur Weyl-duality,
permutation equivalence classes and associated discrete Fourier
transforms as an approach to counting problems and, branched covers and
Hurwitz spaces. Schur-Weyl duality is a powerful relation between
representations of U(N) and representations of symmetric groups.
Representation theory of symmetric groups offers a method to
define nice bases for functions on equivalence classes of permutations.
These bases are useful in counting gauge invariant functions of
matrices or tensors, as well as computing their correlators in physical
theories. In AdS/CFT these bases have proved useful in identifying
local operators in gauge-theory dual to giant gravitons in AdS.
In the simplest cases of gauge-string duality, the known mathematics
of branched covers and Hurwitz spaces provide the mechanism for the
holographic correspondence between gauge invariants and stringy geometry.
(Lecture 3: Hermitian matrix model. Tensor models and Permutation centralizer al- gebras. Using permutation equivalences to count matrix/tensor invariants and compute correlators. Relations to covering spaces.)
These lectures will be focused on aspects of combinatorics relevant to gauge-string duality (holography).
The physical theories we will discuss include two dimensional Yang Mills
theory, four-dimensional N=4 super Yang Mills
theory with U(N) gauge group, Matrix and tensor models.
The key mathematical concepts include : Schur Weyl-duality,
permutation equivalence classes and associated discrete Fourier
transforms as an approach to counting problems and, branched covers and
Hurwitz spaces. Schur-Weyl duality is a powerful relation between
representations of U(N) and representations of symmetric groups.
Representation theory of symmetric groups offers a method to
define nice bases for functions on equivalence classes of permutations.
These bases are useful in counting gauge invariant functions of
matrices or tensors, as well as computing their correlators in physical
theories. In AdS/CFT these bases have proved useful in identifying
local operators in gauge-theory dual to giant gravitons in AdS.
In the simplest cases of gauge-string duality, the known mathematics
of branched covers and Hurwitz spaces provide the mechanism for the
holographic correspondence between gauge invariants and stringy geometry.
(Lecture 3: Hermitian matrix model. Tensor models and Permutation centralizer al- gebras. Using permutation equivalences to count matrix/tensor invariants and compute correlators. Relations to covering spaces.)
Posted by: QMW