Triangle Seminars
Tuesday, 12 May 2020
Phenomenological Applications of the EFTs for Condensed Matter
Angelo Esposito
(Ecole polytechnique federale de Lausanne)
Abstract:
In this talk I will review the general ideas behind the recently developed relativistic effective field theories (EFTs) for different phases of matter (spontaneous symmetry breaking, Goldstone theorem, etc.). I will put particular emphasis on concretely building an EFT for the description of collective excitations in zero-temperature superfluids, which is the simplest of these theories. I will then argue that these methods, borrowed from high energy theory ideology, are mature enough to be successfully applied to phenomenologically relevant problems. In this direction, I will present two applications: (1) the calculation of the gravitational mass transported by a sound wave in a nonrelativistic medium (superfluid, fluid and solid), and (2) the study of the response of a He-4 detector to the passage of sub-MeV dark matter particle. ––- Follow the link in use since May 5th or contact the organisers (Antoine Bourget and Edoardo Vescovi). Student introduction at 13:00.
In this talk I will review the general ideas behind the recently developed relativistic effective field theories (EFTs) for different phases of matter (spontaneous symmetry breaking, Goldstone theorem, etc.). I will put particular emphasis on concretely building an EFT for the description of collective excitations in zero-temperature superfluids, which is the simplest of these theories. I will then argue that these methods, borrowed from high energy theory ideology, are mature enough to be successfully applied to phenomenologically relevant problems. In this direction, I will present two applications: (1) the calculation of the gravitational mass transported by a sound wave in a nonrelativistic medium (superfluid, fluid and solid), and (2) the study of the response of a He-4 detector to the passage of sub-MeV dark matter particle. ––- Follow the link in use since May 5th or contact the organisers (Antoine Bourget and Edoardo Vescovi). Student introduction at 13:00.
Posted by: IC
Wednesday, 13 May 2020
(Quantum) Higher Spin Gravity and Physics
Evgeny Skvortsov
(Albert Einstein Institute (Potsdam))
Abstract:
I will give a general overview of Higher Spin Gravities and also discuss the recent developments
that give a class of models where UV-divergences of Einstein gravity cancel out thanks to the higher spin symmetry.
At the end I will discuss the relation between Higher Spin Gravities and a class of conformal field theories in three dimensions
that describe the physics of many second order phase transitions in the real world and have been recently conjectured to exhibit a number
of remarkable dualities, in particular the three-dimensional bosonization duality. I will show how Higher Spin Gravity can help to prove the dualities
and how it makes new predictions. The relation to QCD and self-dual Yang-Mills will also be discussed.
I will give a general overview of Higher Spin Gravities and also discuss the recent developments
that give a class of models where UV-divergences of Einstein gravity cancel out thanks to the higher spin symmetry.
At the end I will discuss the relation between Higher Spin Gravities and a class of conformal field theories in three dimensions
that describe the physics of many second order phase transitions in the real world and have been recently conjectured to exhibit a number
of remarkable dualities, in particular the three-dimensional bosonization duality. I will show how Higher Spin Gravity can help to prove the dualities
and how it makes new predictions. The relation to QCD and self-dual Yang-Mills will also be discussed.
Posted by: IC
Thursday, 14 May 2020
An exact AdS/CFT duality (please email p.agarwal AT qmul.ac.uk for the zoom link)
Matthias Gaberdiel
(ETH Zurich)
Abstract:
String theory on AdS3 x S3 x T4 with one unit of NS-NS flux is argued to be exactly dual to the symmetric orbifold of T4 in the large N limit. The string theory background can be described in terms of a solvable world-sheet theory. This allows one to compute the complete single-string spacetime spectrum and thereby demonstrate that it agrees with the that of the symmetric orbifold of T4. Furthermore, the structure of the symmetric orbifold correlators can be reproduced from the world-sheet perspective.
String theory on AdS3 x S3 x T4 with one unit of NS-NS flux is argued to be exactly dual to the symmetric orbifold of T4 in the large N limit. The string theory background can be described in terms of a solvable world-sheet theory. This allows one to compute the complete single-string spacetime spectrum and thereby demonstrate that it agrees with the that of the symmetric orbifold of T4. Furthermore, the structure of the symmetric orbifold correlators can be reproduced from the world-sheet perspective.
Posted by: QMW
Friday, 15 May 2020
Wilson loops as Matrix Product States (NOTE UNUSUAL TIME AND DAY)
Shota Komatsu
(IAS)
Abstract:
In his paper in 1979, Polyakov envisaged a possibility of reformulating the gauge theory as a Principal Chiral Model defined on a space of loops and discussed "the loop-space integrability". This idea, together with a closely related idea of the loop equation, led to numerous important results in matrix models and 2d gauge theories, but its application to four-dimensional gauge theories had only limited success. Now, after 50 years, we have a concrete example of integrable four-dimensional gauge theory, N=4 SYM. However integrability in N=4 SYM is formulated mostly in terms of local operators, although important progress has been made in constructing the Yangian for the Wilson loops. In this talk, I will present a framework which would bridge these two distant notions of integrabililty. The key player in the story is a correlation function of a local operator and the Wilson loop. I reformulate the gauge-theory computation of this observable as an overlap between an energy eigenstate of a spin chain and a matrix product state (MPS). Unlike standard MPS's discussed in the literature, our MPS has infinite bond dimensions in order to accommodate infinite dimensionality of the space of loops. It provides an "intertwiner" between integrable structures of the local operators and the Wilson loops, and in particular implies the existence of a special set of deformations of the Wilson loop which satisfy the QQ-relation. I will also explain how to formulate a nonperturbative bootstrap program based on the results obtained in this framework and compute the correlator of the circular BPS Wilson loop and general non-BPS operators at finite coupling, emphasizing the relation to and the difference from other observables that were computed by a similar approach.
––––––––-
Part of London Integrability Journal Club. Please register using the form at integrability-london.weebly.com
In his paper in 1979, Polyakov envisaged a possibility of reformulating the gauge theory as a Principal Chiral Model defined on a space of loops and discussed "the loop-space integrability". This idea, together with a closely related idea of the loop equation, led to numerous important results in matrix models and 2d gauge theories, but its application to four-dimensional gauge theories had only limited success. Now, after 50 years, we have a concrete example of integrable four-dimensional gauge theory, N=4 SYM. However integrability in N=4 SYM is formulated mostly in terms of local operators, although important progress has been made in constructing the Yangian for the Wilson loops. In this talk, I will present a framework which would bridge these two distant notions of integrabililty. The key player in the story is a correlation function of a local operator and the Wilson loop. I reformulate the gauge-theory computation of this observable as an overlap between an energy eigenstate of a spin chain and a matrix product state (MPS). Unlike standard MPS's discussed in the literature, our MPS has infinite bond dimensions in order to accommodate infinite dimensionality of the space of loops. It provides an "intertwiner" between integrable structures of the local operators and the Wilson loops, and in particular implies the existence of a special set of deformations of the Wilson loop which satisfy the QQ-relation. I will also explain how to formulate a nonperturbative bootstrap program based on the results obtained in this framework and compute the correlator of the circular BPS Wilson loop and general non-BPS operators at finite coupling, emphasizing the relation to and the difference from other observables that were computed by a similar approach.
––––––––-
Part of London Integrability Journal Club. Please register using the form at integrability-london.weebly.com
Posted by: andrea