Triangle Seminars
June 2013
Thu
27 Jun 2013
Hitchin systems, spin chains from 3d mirror symmetry
Peter Koroteev
(Perimeter)
Abstract:
I will discuss some interesting connections between quantum and classical integrable systems (e.g. Hitchin system vs. quantum spin chains) in the context of 3 dimensional quiver gauge theories. Gauge theory dualities (Mirror symmetry, Seiberg duality) have direct counterparts on the integrability side.
I will discuss some interesting connections between quantum and classical integrable systems (e.g. Hitchin system vs. quantum spin chains) in the context of 3 dimensional quiver gauge theories. Gauge theory dualities (Mirror symmetry, Seiberg duality) have direct counterparts on the integrability side.
Posted by: IC
Wed
26 Jun 2013
Thermodynamics of black M-branes from SCFTs
Shotaro Shiba
(KEK)
Abstract:
We discuss thermodynamics of N M2- and M5-branes by using the method proposed by Smilga and Wiseman, which explains the black Dp-brane thermodynamics from the maximally supersymmetric U(N) Yang-Mills theories. As result we obtain the consistent results with the predictions from the eleven-dimensional supergravity by very simple calculations: The free energy of M2-branes is evaluated by using ABJM theory as F ~ N^{3/2}k^{1/2}T^3, and that of M5-branes is estimated by assuming some natural properties of 6d conformal field theory as F ~ N^3T^6.
We discuss thermodynamics of N M2- and M5-branes by using the method proposed by Smilga and Wiseman, which explains the black Dp-brane thermodynamics from the maximally supersymmetric U(N) Yang-Mills theories. As result we obtain the consistent results with the predictions from the eleven-dimensional supergravity by very simple calculations: The free energy of M2-branes is evaluated by using ABJM theory as F ~ N^{3/2}k^{1/2}T^3, and that of M5-branes is estimated by assuming some natural properties of 6d conformal field theory as F ~ N^3T^6.
Posted by: IC
Mon
24 Jun 2013
Closed formulae for superstring tree amplitudes: Multiple zeta values and the Drinfeld associator
Oliver Schlotterer
(AEI Potsdam and DAMTP)
Abstract:
We discuss tree level scattering of any number of massless open superstring states on a worldsheet of disk topology. The entire state dependence of the tree amplitude can be expressed in terms of gauge theory subamplitudes from the point particle limit. The string corrections entering through momentum dependent integrals over the disk boundary can be disentangled from the YM seeds and analyzed separately. Their power series expansion in the string length and momenta involves multiple zeta values (MZVs). We review some mathematical background on MZVs and the network of relations between them. The explicit form of any tree level string correction to YM theory is derived from the generating function of MZVs – the Drinfeld associator. It interpolates between the worldsheet integrals in N-point and (N-1)-point scattering and leads to a recursive formula for the momentum expansion of any disk amplitude. Our results apply for any number of spacetime dimensions or supersymmetries and chosen helicity configurations.
We discuss tree level scattering of any number of massless open superstring states on a worldsheet of disk topology. The entire state dependence of the tree amplitude can be expressed in terms of gauge theory subamplitudes from the point particle limit. The string corrections entering through momentum dependent integrals over the disk boundary can be disentangled from the YM seeds and analyzed separately. Their power series expansion in the string length and momenta involves multiple zeta values (MZVs). We review some mathematical background on MZVs and the network of relations between them. The explicit form of any tree level string correction to YM theory is derived from the generating function of MZVs – the Drinfeld associator. It interpolates between the worldsheet integrals in N-point and (N-1)-point scattering and leads to a recursive formula for the momentum expansion of any disk amplitude. Our results apply for any number of spacetime dimensions or supersymmetries and chosen helicity configurations.
Posted by: IC
Wed
19 Jun 2013
The large D limit of General Relativity
Roberto Emparan
(ICREA and U. de Barcelona)
Abstract:
Although at first sight it may seem an odd idea, I will argue that it is actually quite natural to investigate the properties of General Relativity and its black holes in the limit in which the number of spacetime dimensions grows to infinity. The theory simplifies dramatically: it reduces to a theory of non-interacting particles, of finite radius but vanishingly small cross sections, which do not emit nor absorb radiation of any finite frequency. This leads to efficient calculational approaches in an expansion around this limit, as well as to intriguing connections to low-dimensional string-theory black holes.
Although at first sight it may seem an odd idea, I will argue that it is actually quite natural to investigate the properties of General Relativity and its black holes in the limit in which the number of spacetime dimensions grows to infinity. The theory simplifies dramatically: it reduces to a theory of non-interacting particles, of finite radius but vanishingly small cross sections, which do not emit nor absorb radiation of any finite frequency. This leads to efficient calculational approaches in an expansion around this limit, as well as to intriguing connections to low-dimensional string-theory black holes.
Posted by: IC
Mon
17 Jun 2013
Aspects of M-theory and extended geometries
David Berman
(QMUL)
Wed
12 Jun 2013
M5-brane indices from 5d gauge theories
Seok Kim
(Seoul National U.)
Abstract:
From the supersymmetric partition functions of gauge theories
on S5 and CP2 x S1, we calculate the superconformal index of
the 6d (2,0) SCFT on S5 x S1 and explore its physics.
From the supersymmetric partition functions of gauge theories
on S5 and CP2 x S1, we calculate the superconformal index of
the 6d (2,0) SCFT on S5 x S1 and explore its physics.
Posted by: IC
Wed
5 Jun 2013
Partition Functions in Three Dimensions and ''Deriving'' Mirror Symmetry
Anindya Dey
(Univ. of Texas at Austin)
Abstract:
I will review the basic techniques and ideas involved in the study of dualities in D=3,N=4 supersymmetric gauge theories using partition functions on a sphere and demonstrate how these partition functions can provide an extremely non-trivial check of mirror symmetry for a large class of quiver gauge theories. In particular, I will focus on theories whose Type IIB descriptions involve D3 branes ending on orbifold/orientifold 5-planes. In addition to providing a convincing check, this procedure allows one to extract important information about the duality like the "mirror map" rather trivially.
I will review the basic techniques and ideas involved in the study of dualities in D=3,N=4 supersymmetric gauge theories using partition functions on a sphere and demonstrate how these partition functions can provide an extremely non-trivial check of mirror symmetry for a large class of quiver gauge theories. In particular, I will focus on theories whose Type IIB descriptions involve D3 branes ending on orbifold/orientifold 5-planes. In addition to providing a convincing check, this procedure allows one to extract important information about the duality like the "mirror map" rather trivially.
Posted by: IC
May 2013
Thu
30 May 2013
D-Branes, Matrices and Emergent Space
Frank Ferrari
(ULB and International Solvay Institute)
Abstract:
We explain how to define, in matrix (gauge) field theory, the notion of the effective action of k ``probe'' branes in the presence of N ``background'' branes on which the field theory lives. The analysis of the large N planar diagram expansion which computes the effective action yields a simple and generic mechanism explaining the emergence of holographic space dimensions. The resulting effective action matches the non-abelian D-brane action in the closed string background dual to the field theory. We shall discuss briefly a few explicit examples, and also provide a general introduction to the notion of emerging space.
We explain how to define, in matrix (gauge) field theory, the notion of the effective action of k ``probe'' branes in the presence of N ``background'' branes on which the field theory lives. The analysis of the large N planar diagram expansion which computes the effective action yields a simple and generic mechanism explaining the emergence of holographic space dimensions. The resulting effective action matches the non-abelian D-brane action in the closed string background dual to the field theory. We shall discuss briefly a few explicit examples, and also provide a general introduction to the notion of emerging space.
Posted by: IC
Wed
29 May 2013
Instability of extremal black holes
📍 London
Stefanos Aretakis
(Princeton)
Abstract:
In this talk I will show that gauge-invariant derivatives of scalar fields grow asymptotically along the event horizon of extremal black holes. This growth originates from conservation laws on such horizons. The resulted conserved quantities can be seen as a natural generalization of the Newman-Penrose constants along null infinity. I will also present recent generalizations by Reall and Lucietti concerning electromagnetic and linearized gravitational perturbations of extremal black holes.
In this talk I will show that gauge-invariant derivatives of scalar fields grow asymptotically along the event horizon of extremal black holes. This growth originates from conservation laws on such horizons. The resulted conserved quantities can be seen as a natural generalization of the Newman-Penrose constants along null infinity. I will also present recent generalizations by Reall and Lucietti concerning electromagnetic and linearized gravitational perturbations of extremal black holes.
Posted by: KCL
Wed
22 May 2013
Beyond symmetry in higher spin holography
Eric Perlmutter
(DAMTP, Cambridge)
Abstract:
We present a collection of results supporting holographic dualities between 3D higher spin gravity and 2D higher spin-symmetric minimal model CFTs at large central charge, focusing on those that are not fixed by higher spin symmetry alone. This includes the first bulk-boundary matching of correlators in 3D higher spin gravity whose functional form is not fixed by conformal invariance, namely, 4-point functions of certain scalar primary operators. In the bulk, this involves the study of propagating scalars in higher spin gravitational backgrounds, which will also help clarify what constitutes a higher spin black hole.
We present a collection of results supporting holographic dualities between 3D higher spin gravity and 2D higher spin-symmetric minimal model CFTs at large central charge, focusing on those that are not fixed by higher spin symmetry alone. This includes the first bulk-boundary matching of correlators in 3D higher spin gravity whose functional form is not fixed by conformal invariance, namely, 4-point functions of certain scalar primary operators. In the bulk, this involves the study of propagating scalars in higher spin gravitational backgrounds, which will also help clarify what constitutes a higher spin black hole.
Posted by: IC
Tue
21 May 2013
BPS/CFT correspondence and Quantum hydrodynamics
Nikita Nekrasov
(IHES)
Abstract:
I will review the intermediate long wave equation which interpolates between the celebrated Korteweg-de Vries and Benjamin-Ono equations, describing the one-dimensional waves in a shallow and deep water, respectively. The quantum version of this equation is of some interest to the theory of quantum wires and other quasi-one dimensional condensed matter systems. I will explain the unexpected connection of this equation to the dynamics of gauge theories in two, four, and six dimensions. This connection is one of the applications of the BPS/CFT correspondence.
Based on the work in progress with Andrei Okounkov
I will review the intermediate long wave equation which interpolates between the celebrated Korteweg-de Vries and Benjamin-Ono equations, describing the one-dimensional waves in a shallow and deep water, respectively. The quantum version of this equation is of some interest to the theory of quantum wires and other quasi-one dimensional condensed matter systems. I will explain the unexpected connection of this equation to the dynamics of gauge theories in two, four, and six dimensions. This connection is one of the applications of the BPS/CFT correspondence.
Based on the work in progress with Andrei Okounkov
Posted by: IC
Sat
11 May 2013
SMUK – String Math UK 2013
. .
(Surrey)
Abstract:
http://personal.maths.surrey.ac.uk/st/M.Wolf/conferences/smuk2013/index.html
http://personal.maths.surrey.ac.uk/st/M.Wolf/conferences/smuk2013/index.html
Posted by: KCL
Fri
10 May 2013
SMUK – String Math UK 2013
. .
(Surrey)
Abstract:
http://personal.maths.surrey.ac.uk/st/M.Wolf/conferences/smuk2013/index.html
http://personal.maths.surrey.ac.uk/st/M.Wolf/conferences/smuk2013/index.html
Posted by: KCL
Wed
8 May 2013
Unification of Type IIA and IIB Supergravities
📍 London
Jeong-Hyuck Park
(Sogang University Seoul and DAMTP Cambridge)
Abstract:
To the full order in fermions, we construct D = 10 type II supersymmetric double field theory. We spell the precise N = 2 supersymmetry transformation rules as for 32 supercharges. In terms of a stringy differential geometry beyond Riemann, the constructed action unifies type IIA and IIB supergravities in a manifestly covariant manner with respect to O(10, 10) T-duality and a ‘pair’ of local Lorentz groups, or Spin(1, 9) × Spin(9, 1), besides the usual general covariance of supergravities or the generalized diffeomorphism. The distinction of IIA and IIB may arise after a diagonal gauge fixing of the Lorentz groups. They are identified as two different types of ‘solutions’ rather than two different theories.
References: arXiv:1210.5078 (N=2) arXiv:1206.3478 (bosonic N=2) arXiv:1112.0069 (N=1)
To the full order in fermions, we construct D = 10 type II supersymmetric double field theory. We spell the precise N = 2 supersymmetry transformation rules as for 32 supercharges. In terms of a stringy differential geometry beyond Riemann, the constructed action unifies type IIA and IIB supergravities in a manifestly covariant manner with respect to O(10, 10) T-duality and a ‘pair’ of local Lorentz groups, or Spin(1, 9) × Spin(9, 1), besides the usual general covariance of supergravities or the generalized diffeomorphism. The distinction of IIA and IIB may arise after a diagonal gauge fixing of the Lorentz groups. They are identified as two different types of ‘solutions’ rather than two different theories.
References: arXiv:1210.5078 (N=2) arXiv:1206.3478 (bosonic N=2) arXiv:1112.0069 (N=1)
Posted by: KCL
Wed
8 May 2013
Aspects of Gauge-Strings Duality
Carlos Nunez
(Swansea)
Abstract:
I will discuss recent developments in the duality between gauge-fields and Strings.
I will discuss recent developments in the duality between gauge-fields and Strings.
Posted by: IC
Thu
2 May 2013
TBA
Jerome Gauntlett
(Imperial College London)
Wed
1 May 2013
Exploring the 4d Superconformal Zoo
Brian Wecht
(Queen Mary University of London)
Abstract:
**Polygon Seminar**
Over the past several years, it has become increasingly apparent that many interesting and tractable superconformal field theories (SCFTs) can be realized without resorting to a UV Lagrangian description. Although many of these theories have N=2 supersymmetry, these is an even larger class of N=1 theories that can be studied, certain aspects of which remain calculable despite the reduced amount of supersymmetry. In this talk, I will give an introduction to these N=1 theories, how they can be realized via M-theory and F-theory, and which tools we can use to explore them.
**Polygon Seminar**
Over the past several years, it has become increasingly apparent that many interesting and tractable superconformal field theories (SCFTs) can be realized without resorting to a UV Lagrangian description. Although many of these theories have N=2 supersymmetry, these is an even larger class of N=1 theories that can be studied, certain aspects of which remain calculable despite the reduced amount of supersymmetry. In this talk, I will give an introduction to these N=1 theories, how they can be realized via M-theory and F-theory, and which tools we can use to explore them.
Posted by: IC
April 2013
Mon
29 Apr 2013
Scanning for Swiss Cheese Calabi-Yau Threefolds
Vishnu Jejjala
(Witwatersrand)
Thu
25 Apr 2013
TBA
Ralph Blumenhagen
Wed
24 Apr 2013
Functional Bethe Ansatz for AdS/CFT integrability
📍 London
Dmytro Volin
(Nordita)
Abstract:
Computation of conformal dimensions in planar N=4 SYM using integrability techniques was a hot topic during the last decade, with more than thousand publications devoted to it. I will tell you about our new results in this domain: Instead of the Y-system used previously, we are now able to encode the conformal dimensions, at any value of the 't Hooft coupling, in much simpler way: through a Riemann-Hilbert problem. This appears to be not only a very beautiful mathematical setup, but also the most efficient approach to explicitly compute the dimensions. For instance, we've analytically computed the so called Konishi anomalous dimension up to 8 loops in perturbation theory.
Computation of conformal dimensions in planar N=4 SYM using integrability techniques was a hot topic during the last decade, with more than thousand publications devoted to it. I will tell you about our new results in this domain: Instead of the Y-system used previously, we are now able to encode the conformal dimensions, at any value of the 't Hooft coupling, in much simpler way: through a Riemann-Hilbert problem. This appears to be not only a very beautiful mathematical setup, but also the most efficient approach to explicitly compute the dimensions. For instance, we've analytically computed the so called Konishi anomalous dimension up to 8 loops in perturbation theory.
Posted by: KCL
Thu
18 Apr 2013
TBA
Emil Bjerrum-Bohr
Wed
17 Apr 2013
Functional Bethe Ansatz for AdS/CFT spectrum
Dmytro Volin
(Nordita)
Abstract:
Computation of conformal dimensions in planar N=4 SYM using integrability techniques was a hot topic during the last decade, with more than thousand publications devoted to it. I will tell you about our new results in this domain: Instead of the Y-system used previously, we are now able to encode the conformal dimensions, at any value of the 't Hooft coupling, in much simpler way: through a Riemann-Hilbert problem. This appears to be not only a very beautiful mathematical setup, but also the most efficient approach to explicitly compute the dimensions. For instance, we've analytically computed the so called Konishi anomalous dimension up to 8 loops in perturbation theory. The talk will include a pedagogical overview of the subject, no special knowledge in this domain is required.
Computation of conformal dimensions in planar N=4 SYM using integrability techniques was a hot topic during the last decade, with more than thousand publications devoted to it. I will tell you about our new results in this domain: Instead of the Y-system used previously, we are now able to encode the conformal dimensions, at any value of the 't Hooft coupling, in much simpler way: through a Riemann-Hilbert problem. This appears to be not only a very beautiful mathematical setup, but also the most efficient approach to explicitly compute the dimensions. For instance, we've analytically computed the so called Konishi anomalous dimension up to 8 loops in perturbation theory. The talk will include a pedagogical overview of the subject, no special knowledge in this domain is required.
Posted by: IC
Mon
15 Apr 2013
Holographic type II Goldstone modes
Luis Melgar
(IFT, UAM)
Abstract:
We study a holographic model dual to a CFT in 2+1 dimensions at finite temperature and chemical potential with a global U(2) symmetry. At large enough chemical potential spontaneous symmetry breaking occurs and breaks the symmetry to U(1). The non-abelian nature of the symmetry and the explicit Lorentz breaking by the chemical potential imply the presence of an ungapped mode with quadratic dispersion relation in the broken phase. Such modes are called Type II Goldstone bosons and have several distinguished features that we study within the framework of this holographic model.
We study a holographic model dual to a CFT in 2+1 dimensions at finite temperature and chemical potential with a global U(2) symmetry. At large enough chemical potential spontaneous symmetry breaking occurs and breaks the symmetry to U(1). The non-abelian nature of the symmetry and the explicit Lorentz breaking by the chemical potential imply the presence of an ungapped mode with quadratic dispersion relation in the broken phase. Such modes are called Type II Goldstone bosons and have several distinguished features that we study within the framework of this holographic model.
Posted by: IC
Tue
9 Apr 2013
Giant D5 brane Holographic Quantum Hall States
📍 London
Gordon Semenoff
(U. British Columbia)
Mon
8 Apr 2013
Landau levels and incompressible states in dense holographic matter
Gordon Semenoff
(U. British Columbia)
March 2013
Thu
28 Mar 2013
Motivic Multiple Zeta Values and Superstring Amplitudes
Oliver Schlotterer
(Albert Einstein Institute)
Abstract:
I will discuss the mathematical structure of tree level amplitudes among massless superstring states. String corrections to these amplitudes take a compact and elegant form once the contributions from different classes of multiple zeta values (MZVs) are disentangled. The idea is to lift MZVs to their motivic versions endowed with a Hopf algebra structure: It induces an isomorphism which casts the amplitudes into a very symmetric form and represents the generalization of the symbol of a transcendental function. I will also comment on generalizations to loop amplitudes.
I will discuss the mathematical structure of tree level amplitudes among massless superstring states. String corrections to these amplitudes take a compact and elegant form once the contributions from different classes of multiple zeta values (MZVs) are disentangled. The idea is to lift MZVs to their motivic versions endowed with a Hopf algebra structure: It induces an isomorphism which casts the amplitudes into a very symmetric form and represents the generalization of the symbol of a transcendental function. I will also comment on generalizations to loop amplitudes.
Posted by: QMW
Wed
27 Mar 2013
U(1) Symmetries in Global F-Theory Compactifications with GUTs
📍 London
Christoph Mayrhofer
(Heidelberg)
Abstract:
In this talk we will describe the construction of F-Theory GUT models for elliptically fibred Calabi-Yau fourfolds admitting a non-trivial Mordell-Weil group. We work out the matter spectrum and Yukawa couplings, including singlets, for these geometries and present the fluxes corresponding to the U(1) symmetries.'
In this talk we will describe the construction of F-Theory GUT models for elliptically fibred Calabi-Yau fourfolds admitting a non-trivial Mordell-Weil group. We work out the matter spectrum and Yukawa couplings, including singlets, for these geometries and present the fluxes corresponding to the U(1) symmetries.'
Posted by: KCL
Wed
27 Mar 2013
Stationary holographic plasma quenches and numerical methods for non-Killing horizons
Pau Figueras
(DAMTP, Cambridge)
Abstract:
In this talk I will explain a new method to numerically construct stationary black holes with non-Killing horizons. As an example, we will use AdS/CFT to describe a time-independent CFT plasma flowing through a static spacetime which asymptotes to Minkowski in the flow's past and future, with a varying spatial geometry in-between. When the boundary geometry varies slowly, the holographic stress tensor is well-described by viscous hydrodynamics. For fast variations it is not, and the solutions are stationary analogs of dynamical quenches, with the plasma being suddenly driven out of equilibrium. We find evidence that these flows become unstable for sufficiently strong quenches and speculate that the instability may be turbulent. The gravitational dual of these flows are the first examples of
stationary black holes with non-Killing horizons.
In this talk I will explain a new method to numerically construct stationary black holes with non-Killing horizons. As an example, we will use AdS/CFT to describe a time-independent CFT plasma flowing through a static spacetime which asymptotes to Minkowski in the flow's past and future, with a varying spatial geometry in-between. When the boundary geometry varies slowly, the holographic stress tensor is well-described by viscous hydrodynamics. For fast variations it is not, and the solutions are stationary analogs of dynamical quenches, with the plasma being suddenly driven out of equilibrium. We find evidence that these flows become unstable for sufficiently strong quenches and speculate that the instability may be turbulent. The gravitational dual of these flows are the first examples of
stationary black holes with non-Killing horizons.
Posted by: IC
Thu
21 Mar 2013
TBA
David Vegh
Thu
21 Mar 2013
Generalized sine-Gordon models and quantum braided groups
Benoit Vicedo
(U. of Hertfordshire)
Abstract:
I will present the quantized function algebras associated with various examples of generalized sine-Gordon models. These are quadratic algebras of the general Freidel-Maillet type, the classical limits of which reproduce the lattice Poisson algebra recently obtained for these models formulated as gauged Wess-Zumino-Witten models plus an integrable potential. More specifically, I will argue based on these examples that the natural framework for constructing quantum lattice integrable versions of generalized sine-Gordon models is that of affine quantum braided groups.
I will present the quantized function algebras associated with various examples of generalized sine-Gordon models. These are quadratic algebras of the general Freidel-Maillet type, the classical limits of which reproduce the lattice Poisson algebra recently obtained for these models formulated as gauged Wess-Zumino-Witten models plus an integrable potential. More specifically, I will argue based on these examples that the natural framework for constructing quantum lattice integrable versions of generalized sine-Gordon models is that of affine quantum braided groups.
Posted by: IC
Wed
20 Mar 2013
A magic square from Yang-Mills squared
📍 London
Mike Duff
(Imperial College)
Abstract:
We give a division algebra R,C,H,O description of D = 3 Yang-Mills with N = 1,2,4,8 and hence, by tensoring left and right multiplets, a magic square RR, CR, CC, HR, HC, HH, OR, OC, OH, OO description of D = 3 supergravity with N = 2, 3, 4, 5, 6, 8, 9, 10, 12, 16.
We give a division algebra R,C,H,O description of D = 3 Yang-Mills with N = 1,2,4,8 and hence, by tensoring left and right multiplets, a magic square RR, CR, CC, HR, HC, HH, OR, OC, OH, OO description of D = 3 supergravity with N = 2, 3, 4, 5, 6, 8, 9, 10, 12, 16.
Posted by: KCL
Wed
20 Mar 2013
Quivers as Calculators
Sanjaye Ramgoolam
(Queen Mary University of London)
Abstract:
Quivers are directed graphs which encode information about the gauge groups and matter content of a large class of gauge theories, many of which have AdS/CFT duals. The counting of local gauge invariant operators and the computation of their correlators (in the free field limit) can be done by simple diagrammatic manipulations of the quiver, with the help of permutation group theory data. This data includes Young diagrams, Littlewood-Richardson numbers and branching coefficients of permutation groups. Riemann surfaces obtained by thickening the quivers are intimately related to these computations.
Quivers are directed graphs which encode information about the gauge groups and matter content of a large class of gauge theories, many of which have AdS/CFT duals. The counting of local gauge invariant operators and the computation of their correlators (in the free field limit) can be done by simple diagrammatic manipulations of the quiver, with the help of permutation group theory data. This data includes Young diagrams, Littlewood-Richardson numbers and branching coefficients of permutation groups. Riemann surfaces obtained by thickening the quivers are intimately related to these computations.
Posted by: IC
Fri
15 Mar 2013
The story of the projective plane
📍 London
Michael Atiyah
(University of Edinburgh)
Abstract:
This talk will have three parts
1. Past story - classical projective planes
2. Unfinished story - topology of the projective plane
3. Fairy story - physics and the projective plane
This talk will have three parts
1. Past story - classical projective planes
2. Unfinished story - topology of the projective plane
3. Fairy story - physics and the projective plane
Posted by: KCL
Thu
14 Mar 2013
TBA
Donal O'Connell
Wed
13 Mar 2013
Tom Kibble and the Early Universe as the Ultimate Experiment
Neil Turok
(Perimeter)
Abstract:
Tom Kibble was a pioneer of the symmetry breaking paradigm in fundamental physics. His view of physics is exceptionally broad, and Tom also led efforts to see how to test ideas of grand unification through exploring their consequences for the very early universe. Over time, this led to new paradigms for cosmology, like cosmic inflation, with a plethora of observational tests. In this talk, I shall review some of Tom's cosmological innovations and also look forward to new and even more fundamental paradigms capable of tackling the big bang singularity.
[Symmetry and Fundamental Physics - Tom Kibble at 80]
Tom Kibble was a pioneer of the symmetry breaking paradigm in fundamental physics. His view of physics is exceptionally broad, and Tom also led efforts to see how to test ideas of grand unification through exploring their consequences for the very early universe. Over time, this led to new paradigms for cosmology, like cosmic inflation, with a plethora of observational tests. In this talk, I shall review some of Tom's cosmological innovations and also look forward to new and even more fundamental paradigms capable of tackling the big bang singularity.
[Symmetry and Fundamental Physics - Tom Kibble at 80]
Posted by: IC
Wed
13 Mar 2013
The a-theorem and the asymptotics of 4D Quantum Field Theory
📍 London
Riccardo Rattazzi
(EPFL Lausanne)
Abstract:
By generalizing the recent proof of the a-theorem, I derive
constraints on the possible UV and IR asymptotics of 4D Lorentz invariant unitary quantum field theory.
Within perturbation theory the only possible RG flow asymptotic is given by conformal field theory.
I also give a non-perturbative argument that excludes theories with scale
but not conformal invariance.
This argument holds for theories in which the stress-energy tensor
is sufficiently nontrivial in a definite technical sense.
By generalizing the recent proof of the a-theorem, I derive
constraints on the possible UV and IR asymptotics of 4D Lorentz invariant unitary quantum field theory.
Within perturbation theory the only possible RG flow asymptotic is given by conformal field theory.
I also give a non-perturbative argument that excludes theories with scale
but not conformal invariance.
This argument holds for theories in which the stress-energy tensor
is sufficiently nontrivial in a definite technical sense.
Posted by: KCL
Wed
13 Mar 2013
Dynamics of Symmetry Breaking Phase Transitions
Wojciech Zurek
(LANL)
Abstract:
In a seminal 1976 paper Tom Kibble pointed out that, in cosmological phase transitions, causality precludes coordination between local choices of broken symmetry, and, as a result, formation of topological defects is all but inevitable. I shall discuss consequences of this Kibble mechanism for condensed matter physics, where its experimentally testable extrapolation is being studied.
[Symmetry and Fundamental Physics - Tom Kibble at 80]
In a seminal 1976 paper Tom Kibble pointed out that, in cosmological phase transitions, causality precludes coordination between local choices of broken symmetry, and, as a result, formation of topological defects is all but inevitable. I shall discuss consequences of this Kibble mechanism for condensed matter physics, where its experimentally testable extrapolation is being studied.
[Symmetry and Fundamental Physics - Tom Kibble at 80]
Posted by: IC
Wed
13 Mar 2013
The Quest for the Higgs Boson at the LHC
Jim Virdee
(Imperial)
Abstract:
In July 2012 ATLAS and CMS experiments reported the discovery of a Higgs-like boson, most likely confirming the mechanism for generation of mass of fundamental particles put forward by Higgs, Kibble and others in the 1960’s. An outline of the challenges faced during the construction of both the LHC and the experiments will be presented as well as an overview of the current operation and performance. Selected physics results and future aims, in particular those relating to the discovery of the Higgs-like boson, will be discussed.
[Symmetry and Fundamental Physics - Tom Kibble at 80]
In July 2012 ATLAS and CMS experiments reported the discovery of a Higgs-like boson, most likely confirming the mechanism for generation of mass of fundamental particles put forward by Higgs, Kibble and others in the 1960’s. An outline of the challenges faced during the construction of both the LHC and the experiments will be presented as well as an overview of the current operation and performance. Selected physics results and future aims, in particular those relating to the discovery of the Higgs-like boson, will be discussed.
[Symmetry and Fundamental Physics - Tom Kibble at 80]
Posted by: IC
Wed
13 Mar 2013
Tom Kibble: breaking symmetries, breaking ground and the new boson
Steven Weinberg
(Univ. of Texas at Austin)
Abstract:
The talk will describe my first interaction with Tom Kibble, when I visited Imperial College in 1961-2; Tom's ground-breaking work on broken symmetry and the Higgs boson; and how a 1967 paper by Tom laid the foundation for understanding the photon.
[Symmetry and Fundamental Physics - Tom Kibble at 80]
The talk will describe my first interaction with Tom Kibble, when I visited Imperial College in 1961-2; Tom's ground-breaking work on broken symmetry and the Higgs boson; and how a 1967 paper by Tom laid the foundation for understanding the photon.
[Symmetry and Fundamental Physics - Tom Kibble at 80]
Posted by: IC
Fri
8 Mar 2013
Fun in Flatland: an introduction to 3d QFTs
Ken Intriligator
(UC San Diego)
Abstract:
Three dimensional quantum field theories provide a nice testing grounds for exploring quantum field theory phenomena. Very simple UV theories can have highly nontrivial, and rich IR dynamics. These lectures will give a pedagogical review of various aspects of quantum field theory, including instantons, monopoles, the conformal window, vortices, skyrmions, Chern-Simons terms, etc., in the context of 3d quantum field theories. In the context of susy theories, we will review older work on exact results, mirror symmetry and duality, and also mention some more recent results.
Three dimensional quantum field theories provide a nice testing grounds for exploring quantum field theory phenomena. Very simple UV theories can have highly nontrivial, and rich IR dynamics. These lectures will give a pedagogical review of various aspects of quantum field theory, including instantons, monopoles, the conformal window, vortices, skyrmions, Chern-Simons terms, etc., in the context of 3d quantum field theories. In the context of susy theories, we will review older work on exact results, mirror symmetry and duality, and also mention some more recent results.
Posted by: QMW
Thu
7 Mar 2013
Fun in Flatland: an introduction to 3d QFTs
Ken Intriligator
(UC San Diego)
Abstract:
Three dimensional quantum field theories provide a nice testing grounds for exploring quantum field theory phenomena. Very simple UV theories can have highly nontrivial, and rich IR dynamics. These lectures will give a pedagogical review of various aspects of quantum field theory, including instantons, monopoles, the conformal window, vortices, skyrmions, Chern-Simons terms, etc., in the context of 3d quantum field theories. In the context of susy theories, we will review older work on exact results, mirror symmetry and duality, and also mention some more recent results.
Three dimensional quantum field theories provide a nice testing grounds for exploring quantum field theory phenomena. Very simple UV theories can have highly nontrivial, and rich IR dynamics. These lectures will give a pedagogical review of various aspects of quantum field theory, including instantons, monopoles, the conformal window, vortices, skyrmions, Chern-Simons terms, etc., in the context of 3d quantum field theories. In the context of susy theories, we will review older work on exact results, mirror symmetry and duality, and also mention some more recent results.
Posted by: QMW
Wed
6 Mar 2013
Aspects of 3d N=2 Chern-Simons-Matter Theories
Ken Intriligator
(UC San Diego)
Wed
6 Mar 2013
Aspects of AdS_4 Black Holes
Nick Halmagyi
(LPTHE, Paris)
Tue
5 Mar 2013
Fun in Flatland: an introduction to 3d QFTs
Ken Intriligator
(UC San Diego)
Abstract:
Three dimensional quantum field theories provide a nice testing grounds for exploring quantum field theory phenomena. Very simple UV theories can have highly nontrivial, and rich IR dynamics. These lectures will give a pedagogical review of various aspects of quantum field theory, including instantons, monopoles, the conformal window, vortices, skyrmions, Chern-Simons terms, etc., in the context of 3d quantum field theories. In the context of susy theories, we will review older work on exact results, mirror symmetry and duality, and also mention some more recent results.
Three dimensional quantum field theories provide a nice testing grounds for exploring quantum field theory phenomena. Very simple UV theories can have highly nontrivial, and rich IR dynamics. These lectures will give a pedagogical review of various aspects of quantum field theory, including instantons, monopoles, the conformal window, vortices, skyrmions, Chern-Simons terms, etc., in the context of 3d quantum field theories. In the context of susy theories, we will review older work on exact results, mirror symmetry and duality, and also mention some more recent results.
Posted by: QMW
Mon
4 Mar 2013
Fun in Flatland: an introduction to 3d QFTs
Ken Intriligator
(UC San Diego)
Abstract:
Three dimensional quantum field theories provide a nice testing grounds for exploring quantum field theory phenomena. Very simple UV theories can have highly nontrivial, and rich IR dynamics. These lectures will give a pedagogical review of various aspects of quantum field theory, including instantons, monopoles, the conformal window, vortices, skyrmions, Chern-Simons terms, etc., in the context of 3d quantum field theories. In the context of susy theories, we will review older work on exact results, mirror symmetry and duality, and also mention some more recent results.
Three dimensional quantum field theories provide a nice testing grounds for exploring quantum field theory phenomena. Very simple UV theories can have highly nontrivial, and rich IR dynamics. These lectures will give a pedagogical review of various aspects of quantum field theory, including instantons, monopoles, the conformal window, vortices, skyrmions, Chern-Simons terms, etc., in the context of 3d quantum field theories. In the context of susy theories, we will review older work on exact results, mirror symmetry and duality, and also mention some more recent results.
Posted by: QMW
February 2013
Thu
28 Feb 2013
TBA
Robert de Mello Koch
(University of Witwatersrand, South Africa)
Wed
27 Feb 2013
10 to the -5
📍 London
Eugene Lim
(King's College)
Abstract:
I will describe how this number comes from quantum fluctuations during the earliest moments of the Big Bang to become the large scale structure of cosmology that we see today in the skies.
I will describe how this number comes from quantum fluctuations during the earliest moments of the Big Bang to become the large scale structure of cosmology that we see today in the skies.
Posted by: KCL
Wed
27 Feb 2013
Non-Abelian T-duality in sypergravity and the AdS/CFT correspondence
Konstadinos Sfetsos
(Surrey)
Abstract:
We will explain the notion of T-duality in supergravity backgrounds with non-Abelian isometries and non-vanishing RR fluxes. We will then focus on type-II backgrounds on which the duality action preserves supersymmetry. For the case of D3-branes at the tip of the conifold dualising along an SU(2) isometry provides a type-IIA background with M-theory lift is of the type describing duals to certain N=1 SCFT quivers produced by M5-branes wrapping a Riemann surface. In the non-conformal cases we find smooth duals in massive IIA supergravity with a Romans mass naturally quantised. We initiate the interpretation of these geometries in the context of the AdS/CFT correspondence and discuss the fate of various charges under dualisation. The backgrounds suggest a form of Seiberg duality in the dual field theories which also exhibit domain walls and confinement in the infrared.
We will explain the notion of T-duality in supergravity backgrounds with non-Abelian isometries and non-vanishing RR fluxes. We will then focus on type-II backgrounds on which the duality action preserves supersymmetry. For the case of D3-branes at the tip of the conifold dualising along an SU(2) isometry provides a type-IIA background with M-theory lift is of the type describing duals to certain N=1 SCFT quivers produced by M5-branes wrapping a Riemann surface. In the non-conformal cases we find smooth duals in massive IIA supergravity with a Romans mass naturally quantised. We initiate the interpretation of these geometries in the context of the AdS/CFT correspondence and discuss the fate of various charges under dualisation. The backgrounds suggest a form of Seiberg duality in the dual field theories which also exhibit domain walls and confinement in the infrared.
Posted by: IC
Thu
21 Feb 2013
Exact Results in 2d SUSY Theories and Applications
Sungjay Lee
(DAMTP, Cambridge)
Abstract:
I will present the exact computation of the two-dimensional supersymmetric theories on two-sphere using the localization techniques. I will then apply these new results to study type II string compactifications (with emphasis on the exact Kaehler potential of quantum Kaehler moduli of Calabi-Yau geometry and mirror symmetry) and non-rational CFTs.
I will present the exact computation of the two-dimensional supersymmetric theories on two-sphere using the localization techniques. I will then apply these new results to study type II string compactifications (with emphasis on the exact Kaehler potential of quantum Kaehler moduli of Calabi-Yau geometry and mirror symmetry) and non-rational CFTs.
Posted by: IC
Wed
13 Feb 2013
Superconformal couplings of non-abelian tensor and hypermultiplets in six dimensions
📍 London
Robert Wimmer
(YITP Stony Brook)
Abstract:
We construct six-dimensional (1,0) superconformal models with non-abelian gauge couplings for multiple tensor and hypermultiplets. The non-abelian gauge invariance for the two-form potentials is achieved by the introduction of a hierarchy of forms up to degree four, where the three and four forms are non-dynamical. This circumvents certain no-go theorems and turns out to be essential also for the formulation of supersymmetry. The inclusion of the hypermultiplets completes the field content to that of superconformal (2,0) theories of multiple M5 branes, though only (1,0) supersymmetry is manifestly realized. The interacting tensor and hypermultiplets form together with the other (non-dynamical) forms a new on-shell representation of the (1,0) supersymmetry algebra. In general these models provide only equations of motions. For a subclass also a Lagrangian formulation exists which captures certain aspects of the first order dynamics.
We construct six-dimensional (1,0) superconformal models with non-abelian gauge couplings for multiple tensor and hypermultiplets. The non-abelian gauge invariance for the two-form potentials is achieved by the introduction of a hierarchy of forms up to degree four, where the three and four forms are non-dynamical. This circumvents certain no-go theorems and turns out to be essential also for the formulation of supersymmetry. The inclusion of the hypermultiplets completes the field content to that of superconformal (2,0) theories of multiple M5 branes, though only (1,0) supersymmetry is manifestly realized. The interacting tensor and hypermultiplets form together with the other (non-dynamical) forms a new on-shell representation of the (1,0) supersymmetry algebra. In general these models provide only equations of motions. For a subclass also a Lagrangian formulation exists which captures certain aspects of the first order dynamics.
Posted by: KCL
Wed
13 Feb 2013
Supersymmetry invariants and UV divergences in N=4 supergravity
Guillaume Bossard
(CPHT, Ecole Polytechnique)
Abstract:
I shall discuss the structure of supersymmetry invariants in N=4 supergravity coupled to n vector multiplets, and in particular their transformation properties with respect to duality symmetry. This will permit to discuss the anomalous Ward identities for the duality symmetry, and their consequences on the logarithmic divergences of the theory.
I shall discuss the structure of supersymmetry invariants in N=4 supergravity coupled to n vector multiplets, and in particular their transformation properties with respect to duality symmetry. This will permit to discuss the anomalous Ward identities for the duality symmetry, and their consequences on the logarithmic divergences of the theory.
Posted by: IC
Wed
13 Feb 2013
Instantons in Field Theory and String Theory – Leverhulme Lectures
Massimo Bianchi
Abstract:
QMUL Graduate Lectures
QMUL Graduate Lectures
Posted by: QMW
Wed
13 Feb 2013
Holomorphic blocks in 3 dimensions
📍 London
Sara Pasquetti
(Surrey)
Abstract:
This is the first Polygon meeting, which is meant to be complementary to Triangles, with local speakers.
This is the first Polygon meeting, which is meant to be complementary to Triangles, with local speakers.
Posted by: KCL
Mon
11 Feb 2013
Convexity and Liberation at Large Spin
📍 London
Zohar Komargodski
(Weizmann and IAS Princeton)
Mon
11 Feb 2013
The QCD Flux Tube
📍 London
Zohar Komargodski
(Weizmann and IAS Princeton)
Thu
7 Feb 2013
Scattering in AdS4/CFT3
Silvia Penati
(INFN)
Abstract:
Abstract: Within the context of the AdS4/CFT3 correspondence I will present recent results concerning the evaluation of scattering amplitudes for N=6 Chern-Simons-matter theories. I will discuss their peculiar properties like dualities, symmetries and exponentiation.
Abstract: Within the context of the AdS4/CFT3 correspondence I will present recent results concerning the evaluation of scattering amplitudes for N=6 Chern-Simons-matter theories. I will discuss their peculiar properties like dualities, symmetries and exponentiation.
Posted by: QMW
Wed
6 Feb 2013
Classical and Quantum N=8 Supergravity
📍 London
Gianguido Dall'Agata
(Padova University)
Abstract:
I will present a series of new results on classical and quantum properties of maximal supergravity in 4 dimensions,
emphasizing the role of the recently discovered "new SO(8) theories".
I will explain how this changes our understanding of some general properties of supergravity theories
and comment on the impact of these results on the gauge/gravity correspondence.
I will present a series of new results on classical and quantum properties of maximal supergravity in 4 dimensions,
emphasizing the role of the recently discovered "new SO(8) theories".
I will explain how this changes our understanding of some general properties of supergravity theories
and comment on the impact of these results on the gauge/gravity correspondence.
Posted by: KCL
Wed
6 Feb 2013
Supersymmetric Field Theories on Three-Manifolds and Applications
Cyril Closset
(Weizmann)
Abstract:
In the first part of my talk, I will present a general classification of Riemannian three-manifolds on which one can put 3d N=2 supersymmetric field theories while preserving some amount of supersymmetry. This formalism clarifies the relationship between the extra couplings necessary to preserve supersymmetry in curved space, on the one hand, and various operators of the flat space theory, on the other hand.
In the second part of the talk I will present some simple applications of this formalism. In particular I will present exact results for various two-point functions of N=2 SCFTs which were hitherto out of reach.
In the first part of my talk, I will present a general classification of Riemannian three-manifolds on which one can put 3d N=2 supersymmetric field theories while preserving some amount of supersymmetry. This formalism clarifies the relationship between the extra couplings necessary to preserve supersymmetry in curved space, on the one hand, and various operators of the flat space theory, on the other hand.
In the second part of the talk I will present some simple applications of this formalism. In particular I will present exact results for various two-point functions of N=2 SCFTs which were hitherto out of reach.
Posted by: IC
Wed
6 Feb 2013
Instantons in Field Theory and String Theory – Leverhulme Lectures
Massimo Bianchi
Abstract:
QMUL Graduate Lectures
QMUL Graduate Lectures
Posted by: QMW
Mon
4 Feb 2013
Classical and Quantum N=8 Supergravity
Gianguido Dall'Agata
(Padova)
Abstract:
I will present a series of new results on classical and quantum properties of maximal supergravity in 4 dimensions,
emphasizing the role of the recently discovered "new SO(8) theories".
I will explain how this changes our understanding of some general properties of supergravity theories and comment on the impact of these results on the gauge/gravity correspondence.
I will present a series of new results on classical and quantum properties of maximal supergravity in 4 dimensions,
emphasizing the role of the recently discovered "new SO(8) theories".
I will explain how this changes our understanding of some general properties of supergravity theories and comment on the impact of these results on the gauge/gravity correspondence.
Posted by: IC
January 2013
Thu
31 Jan 2013
Deformed Seiberg-Witten curves for ADE quivers
Daniel Ricci Pacifici
(Padova)
Abstract:
We study N=2 ADE quiver gauge theories in presence of a non-trivial Omega background along a two dimensional plane. In particular we perform a saddle point analysis to the partition function and derive an epsilon-deformed version of Seiberg-Witten like equations. The result can be interpreted as a non-commutative version of the standard Seiberg-Witten curves associated to the quiver theories.
We study N=2 ADE quiver gauge theories in presence of a non-trivial Omega background along a two dimensional plane. In particular we perform a saddle point analysis to the partition function and derive an epsilon-deformed version of Seiberg-Witten like equations. The result can be interpreted as a non-commutative version of the standard Seiberg-Witten curves associated to the quiver theories.
Posted by: IC
Wed
30 Jan 2013
Scalar fields, higher spin black holes and W_N minimal models
📍 London
Eric Perlmutter
(DAMTP Cambridge)
Abstract:
We discuss various recent computations that come to bear on the conjectured holographic duality between Vasiliev's theory of 3d higher spin gravity and families of 2d CFTs with W symmetry, at both zero and finite temperature. These rely on novel, purely algebraic methods for computing bulk-boundary propagators for scalar fields in Vasiliev theory. Among other topics to be discussed, our results further clarify the physical content of the term "higher spin black hole" and the nature of the classical limit required for the duality.
We discuss various recent computations that come to bear on the conjectured holographic duality between Vasiliev's theory of 3d higher spin gravity and families of 2d CFTs with W symmetry, at both zero and finite temperature. These rely on novel, purely algebraic methods for computing bulk-boundary propagators for scalar fields in Vasiliev theory. Among other topics to be discussed, our results further clarify the physical content of the term "higher spin black hole" and the nature of the classical limit required for the duality.
Posted by: KCL
Wed
30 Jan 2013
Holographic d-wave superconductors
Marika Taylor
(Southampton)
Abstract:
In recent years there has ben considerable interest in using holographic methods to model strongly interacting condensed matter systems, including unconventional superconductors. However, many high Tc superconductors exhibit d-wave pairing and a satisfactory holographic realization of d-wave superconductors has been elusive. In this talk we will present a top down model for d-wave superconductors and discuss its phenomenology.
In recent years there has ben considerable interest in using holographic methods to model strongly interacting condensed matter systems, including unconventional superconductors. However, many high Tc superconductors exhibit d-wave pairing and a satisfactory holographic realization of d-wave superconductors has been elusive. In this talk we will present a top down model for d-wave superconductors and discuss its phenomenology.
Posted by: IC
Wed
30 Jan 2013
Instantons in Field Theory and String Theory – Leverhulme Lectures
Massimo Bianchi
Abstract:
QMUL Graduate Lectures
QMUL Graduate Lectures
Posted by: QMW
Tue
29 Jan 2013
Uses of String Theory
David Tong
(DAMTP, Cambridge)
Wed
23 Jan 2013
Large N vector Chern Simons theories and their Vasiliev duals part 1
Shiraz Minwalla
(TIFR)
Abstract:
In this talk we review recent developments in the study of \(U(N)\) Chern Simons theories coupled to matter in the fundamental. The theories we study are not necessarily supersymmetric. These theories are interesting for several reasons. First, it turns out to be possible to exactly compute several quantities in these models in the t'Hooft large N limit at all values of the t'Hooft coupling \(\lambda\). Second, these exact results strongly suggest that previously known Giveon-Kutasov type strong weak coupling dualities for supersymmetric theories extend to nonsupersymmetric theories. Third, several of these theories have conjectured bulk dual descriptions governed by Vasiliev's equations. Finally, theories with two gauge groups and matter in the bifundamental representation effectively reduce to fundamental models in the limit that one of the two gauge groups is much larger than the other, and so also have known Vasiliev dual descriptions. In the context of the N=6 ABJ theory, this observation allows us to find a Vasiliev dual of a field theory with a known string dual, and so realize Vasiliev theory as a limit of string theory.
In this talk we review recent developments in the study of \(U(N)\) Chern Simons theories coupled to matter in the fundamental. The theories we study are not necessarily supersymmetric. These theories are interesting for several reasons. First, it turns out to be possible to exactly compute several quantities in these models in the t'Hooft large N limit at all values of the t'Hooft coupling \(\lambda\). Second, these exact results strongly suggest that previously known Giveon-Kutasov type strong weak coupling dualities for supersymmetric theories extend to nonsupersymmetric theories. Third, several of these theories have conjectured bulk dual descriptions governed by Vasiliev's equations. Finally, theories with two gauge groups and matter in the bifundamental representation effectively reduce to fundamental models in the limit that one of the two gauge groups is much larger than the other, and so also have known Vasiliev dual descriptions. In the context of the N=6 ABJ theory, this observation allows us to find a Vasiliev dual of a field theory with a known string dual, and so realize Vasiliev theory as a limit of string theory.
Posted by: KCL
Wed
23 Jan 2013
Large N vector Chern Simons theories and their Vasiliev duals part 2
Shiraz Minwalla
(TIFR)
Abstract:
In this talk we review recent developments in the study of \(U(N)\) Chern Simons theories coupled to matter in the fundamental. The theories we study are not necessarily supersymmetric. These theories are interesting for several reasons. First, it turns out to be possible to exactly compute several quantities in these models in the t'Hooft large N limit at all values of the t'Hooft coupling \(\lambda\). Second, these exact results strongly suggest that previously known Giveon-Kutasov type strong weak coupling dualities for supersymmetric theories extend to nonsupersymmetric theories. Third, several of these theories have conjectured bulk dual descriptions governed by Vasiliev's equations. Finally, theories with two gauge groups and matter in the bifundamental representation effectively reduce to fundamental models in the limit that one of the two gauge groups is much larger than the other, and so also have known Vasiliev dual descriptions. In the context of the N=6 ABJ theory, this observation allows us to find a Vasiliev dual of a field theory with a known string dual, and so realize Vasiliev theory as a limit of string theory.
In this talk we review recent developments in the study of \(U(N)\) Chern Simons theories coupled to matter in the fundamental. The theories we study are not necessarily supersymmetric. These theories are interesting for several reasons. First, it turns out to be possible to exactly compute several quantities in these models in the t'Hooft large N limit at all values of the t'Hooft coupling \(\lambda\). Second, these exact results strongly suggest that previously known Giveon-Kutasov type strong weak coupling dualities for supersymmetric theories extend to nonsupersymmetric theories. Third, several of these theories have conjectured bulk dual descriptions governed by Vasiliev's equations. Finally, theories with two gauge groups and matter in the bifundamental representation effectively reduce to fundamental models in the limit that one of the two gauge groups is much larger than the other, and so also have known Vasiliev dual descriptions. In the context of the N=6 ABJ theory, this observation allows us to find a Vasiliev dual of a field theory with a known string dual, and so realize Vasiliev theory as a limit of string theory.
Posted by: KCL
Thu
17 Jan 2013
Supergravity from 2 and 3-Algebra Gauge Theory
Henrik Johansson
(CERN)
Wed
16 Jan 2013
Applied localization
📍 London
Konstantin Zarembo
(Nordita)
Abstract:
Localization is a non-perturbative method to exactly compute path integrals in supersymmetric theories. I will describe how localization can be thus used to test holographic duality in a non-conformal setting, namely for N=2* theory, which is a massive deformation of N=4 super Yang-Mills, and for which the dual supergravity background is known explicitly.
Localization is a non-perturbative method to exactly compute path integrals in supersymmetric theories. I will describe how localization can be thus used to test holographic duality in a non-conformal setting, namely for N=2* theory, which is a massive deformation of N=4 super Yang-Mills, and for which the dual supergravity background is known explicitly.
Posted by: KCL
Wed
16 Jan 2013
Takiff superalgebras and related CFT
Andrei Babichenko
(Weizmann)
Abstract:
A class of non-semisimple extensions of Lie superalgebras is studied. They are obtained by adjoining to the superalgebra its adjoint representation as an abelian ideal. When the superalgebra is of affine Kac-Moody type, a generalisation of Sugawara’s construction is shown to give rise to a copy of the Virasoro algebra and so, presumably, to a conformal field theory. Evidence for this is detailed for the extension of the affinisation of the superalgebra gl (1|1): Its highest weight irreducible modules are classified using spectral flow, the irreducible supercharacters are computed and a continuum version of the Verlinde formula is verified to give non-negative integer structure coefficients. Interpreting these coefficients as those of the Grothendieck ring of fusion, partial results on the true fusion ring and its indecomposable structures are deduced.
A class of non-semisimple extensions of Lie superalgebras is studied. They are obtained by adjoining to the superalgebra its adjoint representation as an abelian ideal. When the superalgebra is of affine Kac-Moody type, a generalisation of Sugawara’s construction is shown to give rise to a copy of the Virasoro algebra and so, presumably, to a conformal field theory. Evidence for this is detailed for the extension of the affinisation of the superalgebra gl (1|1): Its highest weight irreducible modules are classified using spectral flow, the irreducible supercharacters are computed and a continuum version of the Verlinde formula is verified to give non-negative integer structure coefficients. Interpreting these coefficients as those of the Grothendieck ring of fusion, partial results on the true fusion ring and its indecomposable structures are deduced.
Posted by: IC
Thu
10 Jan 2013
Conformal Regge Theory
Miguel S. Costa
(Centro de Fisica do Porto)
Abstract:
We generalize Regge theory to correlation functions in conformal field theories. This is done by exploring the analogy between Mellin amplitudes in AdS/CFT and S-matrix elements. In the process, we develop the conformal partial wave expansion in Mellin space, elucidating the analytic structure of the partial amplitudes. We apply the new formalism to the case of four point correlation functions between protected scalar operators in N=4 Super Yang Mills, in cases where the Regge limit is controlled by the leading twist operators associated to the pomeron-graviton Regge trajectory. At weak coupling, we are able to predict to arbitrary high order in the 't Hooft coupling the behaviour near J=1 of the OPE coefficients C_{OOJ} between the external scalars and the spin J leading twist operators. At strong coupling, we use recent results for the anomalous dimension of the leading twist operators to improve current knowledge of the AdS graviton Regge trajectory - in particular, determining the next and next to next leading order corrections to the intercept. Finally, by taking the flat space limit and considering the Virasoro-Shapiro S-matrix element, we compute the strong coupling limit of the OPE coefficient C_{LLJ} between two Lagrangians and the leading twist operators of spin J.
We generalize Regge theory to correlation functions in conformal field theories. This is done by exploring the analogy between Mellin amplitudes in AdS/CFT and S-matrix elements. In the process, we develop the conformal partial wave expansion in Mellin space, elucidating the analytic structure of the partial amplitudes. We apply the new formalism to the case of four point correlation functions between protected scalar operators in N=4 Super Yang Mills, in cases where the Regge limit is controlled by the leading twist operators associated to the pomeron-graviton Regge trajectory. At weak coupling, we are able to predict to arbitrary high order in the 't Hooft coupling the behaviour near J=1 of the OPE coefficients C_{OOJ} between the external scalars and the spin J leading twist operators. At strong coupling, we use recent results for the anomalous dimension of the leading twist operators to improve current knowledge of the AdS graviton Regge trajectory - in particular, determining the next and next to next leading order corrections to the intercept. Finally, by taking the flat space limit and considering the Virasoro-Shapiro S-matrix element, we compute the strong coupling limit of the OPE coefficient C_{LLJ} between two Lagrangians and the leading twist operators of spin J.
Posted by: QMW
Wed
9 Jan 2013
Yet another duality: Nichols algebras and logarithmic two-dimensional CFT models
Alexei M. Semikhatov
(Lebedev Physical Institute)
Abstract:
The task of classifying logarithmic conformal field theories, traditionally considered beyond reach, has become feasible by identifying an algebraic object that largely captures this classification. In some sense, the relevant algebraic tool is a braided analogue of the Howe/Schur–Weyl duality.
The task of classifying logarithmic conformal field theories, traditionally considered beyond reach, has become feasible by identifying an algebraic object that largely captures this classification. In some sense, the relevant algebraic tool is a braided analogue of the Howe/Schur–Weyl duality.
Posted by: IC