Triangle Seminars
Tuesday, 18 Oct 2016
Symmetry and String theory
Menika Sharma
(Allahabad)
Abstract:
String theory in the tensionless limit is expected to have a large gauge symmetry. By recasting string theory on the AdS background as a generalization of Vasiliev's theory of massless higher-spin fields, it has become possible to understand the nature of this symmetry. In this talk, I will first give an overview of three-dimensional Vasiliev theory and its dual CFT. I will then discuss the current understanding of the symmetry algebra of string theory as well as open problems related to it.
String theory in the tensionless limit is expected to have a large gauge symmetry. By recasting string theory on the AdS background as a generalization of Vasiliev's theory of massless higher-spin fields, it has become possible to understand the nature of this symmetry. In this talk, I will first give an overview of three-dimensional Vasiliev theory and its dual CFT. I will then discuss the current understanding of the symmetry algebra of string theory as well as open problems related to it.
Posted by: KCL
On the quantization of a string with endpoint particles and the decay width of the hadronic string
Cobi Sonnenschien
(Tel Aviv)
Abstract:
Holography inspired stringy hadrons (HISH) is a set of models that describe hadrons: mesons, baryons, glueballs and exotic hadrons as strings in four dimensional at space-time. The models are based on a "map" from stringy hadrons of curved holographic confining backgrounds. In the first part of the talk I will review the "derivation" of the models. I will start with a brief reminder of the passage from the original AdS/CFT correspondence to the string/gauge duality of certain favored confining holographic models. I will then describe the string configurations in these holographic backgrounds that correspond to Wilson lines, mesons, baryons, glueballs and exotics. Key ingredients of the four dimensional picture of hadrons are the "string end-point mass" and the "baryonic string vertex". I will determine the classical trajectories of the HISH spectra. I will review the current understanding of the quantization of these hadronic strings. The computation of HISH decay width of hadrons will be described. In the last part of the talk I will summarize the comparison of the outcome of the HISH models with the PDG data about mesons and baryons. I will present the values of the tension, masses and intercepts extracted from best fits to hadron spectra and write down certain predictions for higher excited hadrons. I will present attempts to identify glueballs. The decay width of certain hadrons will be compared with the theoretical calculation. I will suggest a window to the landscape of tetra-quarks and other exotic hadrons.
Holography inspired stringy hadrons (HISH) is a set of models that describe hadrons: mesons, baryons, glueballs and exotic hadrons as strings in four dimensional at space-time. The models are based on a "map" from stringy hadrons of curved holographic confining backgrounds. In the first part of the talk I will review the "derivation" of the models. I will start with a brief reminder of the passage from the original AdS/CFT correspondence to the string/gauge duality of certain favored confining holographic models. I will then describe the string configurations in these holographic backgrounds that correspond to Wilson lines, mesons, baryons, glueballs and exotics. Key ingredients of the four dimensional picture of hadrons are the "string end-point mass" and the "baryonic string vertex". I will determine the classical trajectories of the HISH spectra. I will review the current understanding of the quantization of these hadronic strings. The computation of HISH decay width of hadrons will be described. In the last part of the talk I will summarize the comparison of the outcome of the HISH models with the PDG data about mesons and baryons. I will present the values of the tension, masses and intercepts extracted from best fits to hadron spectra and write down certain predictions for higher excited hadrons. I will present attempts to identify glueballs. The decay width of certain hadrons will be compared with the theoretical calculation. I will suggest a window to the landscape of tetra-quarks and other exotic hadrons.
Posted by: IC
The Quantum Hall Zoo
Carl Turner
(DAMTP)
Abstract:
The Quantum Hall Effect is one of the richest phenomena in condensed matter (now featured in no fewer than three Nobel prizes!). I will introduce and explain it, insofar as we understand it. Towards the end, I will say a few words about work to try and rationalise and relate the many models of the effect.
The Quantum Hall Effect is one of the richest phenomena in condensed matter (now featured in no fewer than three Nobel prizes!). I will introduce and explain it, insofar as we understand it. Towards the end, I will say a few words about work to try and rationalise and relate the many models of the effect.
Posted by: KCL
Wednesday, 19 Oct 2016
Comments on the Space of QFTs
📍 London
Matthew Buican
(Queen Mary University of London)
Abstract:
In the first part of the talk, I will revisit the question of how to decide whether two 4D N=2 superconformal field theories describe the same physics. Time permitting, I will discuss related questions regarding the classification of 2D rational conformal field theories.
In the first part of the talk, I will revisit the question of how to decide whether two 4D N=2 superconformal field theories describe the same physics. Time permitting, I will discuss related questions regarding the classification of 2D rational conformal field theories.
Posted by: KCL
Polygon Seminar: Algebraic methods for classical integrability
Alessandro Torrielli
(Surrey)
Abstract:
We will review a series of algebraic techniques to describe classically integrable systems, with an eye to their quantisation. The topics we shall attempt to cover will be: 1. General introduction to classical integrability and notion of Lax pair 2. Classical r-matrices and exchange relations 3. Belavin-Drinfeld theorems and classifications 4. Quantisation and elements of algebraic Bethe ansatz
We will review a series of algebraic techniques to describe classically integrable systems, with an eye to their quantisation. The topics we shall attempt to cover will be: 1. General introduction to classical integrability and notion of Lax pair 2. Classical r-matrices and exchange relations 3. Belavin-Drinfeld theorems and classifications 4. Quantisation and elements of algebraic Bethe ansatz
Posted by: QMW
Thursday, 20 Oct 2016
Conformal Higher Spin Theory and Twistor Space Actions
Philipp Haehnel
(Trinity College Dublin)
Abstract:
We give an introduction to twistor theory and construct a twistor action for the self-dual part of conformal higher spin theories by treating the integrability condition for the holomorphic structure of a complex deformation of flat twistor space as the equations of motion of those higher spin fields. Analogous to the embedding of Einstein gravity with cosmological constant in Weyl gravity, we identify a ghost-free subsector which generates the unique three-point anti-MHV amplitude consistent with Poincaré invariance and helicity constraints.
We give an introduction to twistor theory and construct a twistor action for the self-dual part of conformal higher spin theories by treating the integrability condition for the holomorphic structure of a complex deformation of flat twistor space as the equations of motion of those higher spin fields. Analogous to the embedding of Einstein gravity with cosmological constant in Weyl gravity, we identify a ghost-free subsector which generates the unique three-point anti-MHV amplitude consistent with Poincaré invariance and helicity constraints.
Posted by: IC
Hexagon form factors in ABJM
Raul Pereira
(Uppsala)
Abstract:
In this talk I will start by reviewing the hexagon bootstrap program for three-point functions in N=4. Then I will explain how to extend those methods to ABJM theory by considering three-point functions whose vacua preserve SU(1|2)xU(1) symmetry. I will show that this symmetry fully constraints the two-particle hexagon form factor and comment on how to construct the multi-particle hexagon. Finally, I will conclude with a summary of the difficulties in implementing this program for ABJM.
In this talk I will start by reviewing the hexagon bootstrap program for three-point functions in N=4. Then I will explain how to extend those methods to ABJM theory by considering three-point functions whose vacua preserve SU(1|2)xU(1) symmetry. I will show that this symmetry fully constraints the two-particle hexagon form factor and comment on how to construct the multi-particle hexagon. Finally, I will conclude with a summary of the difficulties in implementing this program for ABJM.
Posted by: IC