Triangle Seminars
June 2014
Wed
18 Jun 2014
Scattering amplitudes in certain gauged supergravity theories
Radu Roiban
(Penn State)
Wed
11 Jun 2014
Heterotic NS5-branes from closed string tachyon condensation
Inaki Garcia Etxebarria
(MPI, Munich)
Abstract:
I will show how to construct the familiar heterotic NS5 brane as a topological soliton in a supercritical version of heterotic string theory. Closed string tachyon condensation removes the extra dimensions, leaving the NS5 in 10d, in a process highly reminiscent of the K-theoretical description of type II D-branes, but linking
non-trivial gauge bundles and geometry. The construction requires a modification of the anomalous Bianchi identity for H_3 in supercritical heterotic string theory. I will give various proofs for the existence of this modification.
I will show how to construct the familiar heterotic NS5 brane as a topological soliton in a supercritical version of heterotic string theory. Closed string tachyon condensation removes the extra dimensions, leaving the NS5 in 10d, in a process highly reminiscent of the K-theoretical description of type II D-branes, but linking
non-trivial gauge bundles and geometry. The construction requires a modification of the anomalous Bianchi identity for H_3 in supercritical heterotic string theory. I will give various proofs for the existence of this modification.
Posted by: IC
Wed
4 Jun 2014
N = (0, 2) Heterotic Sigma Models: Geometric Structure, Holomorphic Anomaly and Exact Beta Functions
Xiaoyi Cui
(MPI, Bonn)
Abstract:
We study geometric aspects and holomorphic properties of N = (0, 2) Heterotic Sigma Models over symmetric spaces, and derive a number of exact relations for the β functions in terms of the analogy to the NSVZ β function in four-dimensional Yang-Mills. We will show that in spite of the heterotic nature, the isometries are preserved at the quantum level. We will also discuss the N = (0, 2) supercurrent multiplet (the so-called hypercurrent) and its anomalies, as well as the “Konishi anomaly.” This gives us another method for finding two-loop β functions. The talk is based on joint work with J. Chen, M. Shifman and A. Vainshtein.
We study geometric aspects and holomorphic properties of N = (0, 2) Heterotic Sigma Models over symmetric spaces, and derive a number of exact relations for the β functions in terms of the analogy to the NSVZ β function in four-dimensional Yang-Mills. We will show that in spite of the heterotic nature, the isometries are preserved at the quantum level. We will also discuss the N = (0, 2) supercurrent multiplet (the so-called hypercurrent) and its anomalies, as well as the “Konishi anomaly.” This gives us another method for finding two-loop β functions. The talk is based on joint work with J. Chen, M. Shifman and A. Vainshtein.
Posted by: IC
Tue
3 Jun 2014
MOST – Mathematics of String Theory
📍 London
Mathematics of String Theory Workshop Bridgeland Dimofte Fine Gross dela Ossa Keel Hollands Skinner Thomas
(See Abstract for Details)
Abstract:
Workshop information and registration
http://www.mth.kcl.ac.uk/~ss299/MOST/
Workshop information and registration
http://www.mth.kcl.ac.uk/~ss299/MOST/
Posted by: KCL
Mon
2 Jun 2014
MOST – Mathematics of String Theory
📍 London
Mathematics of String Theory Workshop Bridgeland Dimofte Fine Gross dela Ossa Keel Hollands Skinner Thomas
Abstract:
Workshop homepage for information and registration
http://www.mth.kcl.ac.uk/~ss299/MOST/
Workshop homepage for information and registration
http://www.mth.kcl.ac.uk/~ss299/MOST/
Posted by: KCL
May 2014
Thu
29 May 2014
Non-Associative Geometry, Non-Geometric String Backgrounds and Double Field Theory
Dieter Lust
(LMU)
Abstract:
In this talk we discuss the geometric and non-geometric faces of closed string vacua.
The associated closed string geometries are described by new non-commutative as well
as non-associative algebras, which can be characterized by certain 3-cocycles in Lie algebra cohomology.
We present an associated star-product algebra on functions in phase space.
We also discuss some aspects of uncertainty relations, as well as the question,
if the non-associative structures are visible in conformal field theory and in double field theory.
In this talk we discuss the geometric and non-geometric faces of closed string vacua.
The associated closed string geometries are described by new non-commutative as well
as non-associative algebras, which can be characterized by certain 3-cocycles in Lie algebra cohomology.
We present an associated star-product algebra on functions in phase space.
We also discuss some aspects of uncertainty relations, as well as the question,
if the non-associative structures are visible in conformal field theory and in double field theory.
Posted by: QMW
Wed
28 May 2014
Higher Spins in Hyperspace
📍 London
Dmitri Sorokin
(INFN Padova)
Abstract:
I will discuss basic features of a formulation of higher-spin field theory in which conventional space-time gets extended to a hyperspace with a number of extra dimensions that effectively describe the spin degrees of freedom of the fields in the ordinary space-time. In this formulation an infinite number of higher spin fields are packed into a single scalar and spinor field propagating in the hyperspace. The dynamics of higher spin fields is encoded in equations of motion of the scalar and spinor hyperfields. The hyperfield equatons on flat and AdS-like hyperspaces are related to each other by a generalized conformal transformation, which also relates two-, three- and four-point functions in the AdS-like hyperspace to the corresponding correlators in the flat hyperspace.
I will discuss basic features of a formulation of higher-spin field theory in which conventional space-time gets extended to a hyperspace with a number of extra dimensions that effectively describe the spin degrees of freedom of the fields in the ordinary space-time. In this formulation an infinite number of higher spin fields are packed into a single scalar and spinor field propagating in the hyperspace. The dynamics of higher spin fields is encoded in equations of motion of the scalar and spinor hyperfields. The hyperfield equatons on flat and AdS-like hyperspaces are related to each other by a generalized conformal transformation, which also relates two-, three- and four-point functions in the AdS-like hyperspace to the corresponding correlators in the flat hyperspace.
Posted by: KCL
Wed
28 May 2014
Geometric Constraints in Heterotic/F-theory Duality
Lara Anderson
(Virginia Tech)
Abstract:
We systematically analyze a broad class of dual heterotic and F-theory models that give four-dimensional supergravity theories, and compare the geometric constraints on the two sides of the duality. In this talk I will show that F-theory gives new insight into the conditions under which heterotic vector bundles can be constructed. We show that in many cases the F-theory geometry imposes a constraint on the extent to which the gauge group can be enhanced, corresponding to limits on the way in which the heterotic bundle can decompose. We explicitly construct all dual F-theory/heterotic pairs in the class under consideration where the common twofold base surface is toric, and give both toric and non-toric examples of the general results. Finally, we provide evidence for important new aspects of G-flux in four-dimensional compactifications.
We systematically analyze a broad class of dual heterotic and F-theory models that give four-dimensional supergravity theories, and compare the geometric constraints on the two sides of the duality. In this talk I will show that F-theory gives new insight into the conditions under which heterotic vector bundles can be constructed. We show that in many cases the F-theory geometry imposes a constraint on the extent to which the gauge group can be enhanced, corresponding to limits on the way in which the heterotic bundle can decompose. We explicitly construct all dual F-theory/heterotic pairs in the class under consideration where the common twofold base surface is toric, and give both toric and non-toric examples of the general results. Finally, we provide evidence for important new aspects of G-flux in four-dimensional compactifications.
Posted by: IC
Tue
27 May 2014
(Non)-Integrability of Geodesics in D-brane Backgrounds
Oleg Lunin
(Unveristy of Albany)
Abstract:
Motivated by the search for new backgrounds with solvable string theories, the talk classifies the D-brane geometries leading to integrable geodesics. This analysis gives severe restrictions on the potential candidates for integrable string theories.
It is demonstrated that the Hamilton-Jacobi equation for massless geodesics can only separate in elliptic or spherical coordinates, all known integrable backgrounds are covered by this separation, and new examples are constructed. The Killing and Killing-Yano tensors associated with such separation and their transformations under string dualities are also discussed.
Motivated by the search for new backgrounds with solvable string theories, the talk classifies the D-brane geometries leading to integrable geodesics. This analysis gives severe restrictions on the potential candidates for integrable string theories.
It is demonstrated that the Hamilton-Jacobi equation for massless geodesics can only separate in elliptic or spherical coordinates, all known integrable backgrounds are covered by this separation, and new examples are constructed. The Killing and Killing-Yano tensors associated with such separation and their transformations under string dualities are also discussed.
Posted by: IC
Thu
22 May 2014
3d N=4 Gauge Theories, Mirror Symmetry and Hilbert series
Noppadol Mekareeya
(CERN)
Abstract:
This talk focuses on vacuum moduli spaces of N=4 supersymmetric field theories in three dimensions. A particular branch of the moduli space, known as the Coulomb branch, receives quantum corrections. We present an exact result, known as the Hilbert series, that enumerates the operators in the chiral ring of such a quantum Coulomb branch. This exact result can be applied to a large class of 3d supersymmetric field theories, with and without known Lagrangian descriptions. As an application, we present a method to compute partition functions of instantons on C^2 for any simple group, including exceptional and non-simply-laced ones.
This talk focuses on vacuum moduli spaces of N=4 supersymmetric field theories in three dimensions. A particular branch of the moduli space, known as the Coulomb branch, receives quantum corrections. We present an exact result, known as the Hilbert series, that enumerates the operators in the chiral ring of such a quantum Coulomb branch. This exact result can be applied to a large class of 3d supersymmetric field theories, with and without known Lagrangian descriptions. As an application, we present a method to compute partition functions of instantons on C^2 for any simple group, including exceptional and non-simply-laced ones.
Posted by: QMW
Wed
21 May 2014
Localisation and gauge/gravity duality
📍 London
Cremonesi Drukker Shamir Sparks
(-)
Abstract:
This is a one-day meeting on localisation and gauge gravity duality. More information at http://kings-meeting.wikidot.com/
This is a one-day meeting on localisation and gauge gravity duality. More information at http://kings-meeting.wikidot.com/
Posted by: KCL
Mon
19 May 2014
TBA
Vishnu Jejjala
(Witwatersrand)
Thu
15 May 2014
South East Mathematical Physics Seminar
📍 London
South East Mathematical Physics Seminar
(See Abstract for Details)
Abstract:
South East Mathematical Physics Seminar: For details see
http://www.mth.kcl.ac.uk/SEMPS/
Speakers: Leron Borsten,Paul Sutcliffe, Vidas Regelskis, Abera Muhamed, Craig Lawrie
South East Mathematical Physics Seminar: For details see
http://www.mth.kcl.ac.uk/SEMPS/
Speakers: Leron Borsten,Paul Sutcliffe, Vidas Regelskis, Abera Muhamed, Craig Lawrie
Posted by: KCL
Wed
14 May 2014
Generalized entropy and higher derivative Gravity
Joan Camps
(DAMTP Cambridge)
Abstract:
I will discuss the Maldacena-Lewkowycz derivation of the Ryu-Takayangi prescrition for holographic entanglement entropy, and extend it to a more general class of theories of gravity in the bulk. This analysis results in a new euclidean entropy functional, that generalises Wald's entropy. In lorentzian signature, this functional is a natural extension of Wald's black hole entropy to time dependent situations.
I will discuss the Maldacena-Lewkowycz derivation of the Ryu-Takayangi prescrition for holographic entanglement entropy, and extend it to a more general class of theories of gravity in the bulk. This analysis results in a new euclidean entropy functional, that generalises Wald's entropy. In lorentzian signature, this functional is a natural extension of Wald's black hole entropy to time dependent situations.
Posted by: IC
Wed
14 May 2014
Student Triangle Seminar
📍 London
Student Triangle Seminar
(See Abstract for Details)
Abstract:
Student Triangle Seminar!
http://www.mth.kcl.ac.uk/studenttriangle.html
Student Triangle Seminar!
http://www.mth.kcl.ac.uk/studenttriangle.html
Posted by: KCL
Fri
9 May 2014
On M5 branes
Kimyeong Lee
(KIAS)
Fri
9 May 2014
Quiver Gauge Theories and the Moduli Space of Instantons
Amihay Hanany
(Imperial)
Abstract:
Instantons appear in many problems of theoretical physics.
Quiver gauge theories are a rising subject due to its natural emergence in perturbative open string theories.
The talk will discuss features of these two topics and how one can use quiver gauge theories to solve the long standing problem of finding the moduli space of k G instantons on C^2, where G is any simple gauge group, including the non-simply laced cases.
Instantons appear in many problems of theoretical physics.
Quiver gauge theories are a rising subject due to its natural emergence in perturbative open string theories.
The talk will discuss features of these two topics and how one can use quiver gauge theories to solve the long standing problem of finding the moduli space of k G instantons on C^2, where G is any simple gauge group, including the non-simply laced cases.
Posted by: KCL
Thu
8 May 2014
Holographic anyonic superfluidity
Matthew Lippert
(Amsterdam U.)
Abstract:
This talk will be about an unusual type of superfluid, one made up of anyons. I will discuss anyons, their relation to the quantum Hall effect, and how an anyonic superfluid is unlike a typical superfluid. Then I will describe a holographic model of a strongly-coupled anyonic superfluid and the stability of its supercurrents.
This talk will be about an unusual type of superfluid, one made up of anyons. I will discuss anyons, their relation to the quantum Hall effect, and how an anyonic superfluid is unlike a typical superfluid. Then I will describe a holographic model of a strongly-coupled anyonic superfluid and the stability of its supercurrents.
Posted by: QMW
Thu
8 May 2014
New results on AdS black holes
Dietmar Klemm
(Milano 1)
Abstract:
We give a survey on recent results on the physics of black
holes in four-dimensional anti-de Sitter space. In particular, we present a general recipe for constructing rotating black holes in N=2 matter-coupled gauged supergravity. Several physical aspects of these solutions are discussed, like their thermodynamics and dual hydrodynamical interpretation. It turns out that there
exist new exotic black holes whose horizon is a noncompact manifold with finite volume. Finally, we show how to construct multi-centered black hole solutions in anti-de Sitter space.
We give a survey on recent results on the physics of black
holes in four-dimensional anti-de Sitter space. In particular, we present a general recipe for constructing rotating black holes in N=2 matter-coupled gauged supergravity. Several physical aspects of these solutions are discussed, like their thermodynamics and dual hydrodynamical interpretation. It turns out that there
exist new exotic black holes whose horizon is a noncompact manifold with finite volume. Finally, we show how to construct multi-centered black hole solutions in anti-de Sitter space.
Posted by: IC
Wed
7 May 2014
The fermionic basis in sin(h)-Gordon model
📍 London
Stefano Negro
(Durham and Turin)
Abstract:
Recently a powerful approach to the computation of one-point functions in the quantum XXZ spin 1/2 chain has been proposed by Boos, Jimbo, Miwa and Smirnov; this framework relies on the existence of a particular basis in the state space of the theory: the fermionic basis. I will present the construction of these fermions for the scaling limit of inhomogeneous XXZ spin 1/2 chain, the sine-Gordon model, and for its twin, the sinh-Gordon model. If time allows it, I will briefly present a possible interpretation of the fermionic basis and one-point functions in terms of the action of a modified version of the sinh-Gordon model.
Recently a powerful approach to the computation of one-point functions in the quantum XXZ spin 1/2 chain has been proposed by Boos, Jimbo, Miwa and Smirnov; this framework relies on the existence of a particular basis in the state space of the theory: the fermionic basis. I will present the construction of these fermions for the scaling limit of inhomogeneous XXZ spin 1/2 chain, the sine-Gordon model, and for its twin, the sinh-Gordon model. If time allows it, I will briefly present a possible interpretation of the fermionic basis and one-point functions in terms of the action of a modified version of the sinh-Gordon model.
Posted by: KCL
Thu
1 May 2014
The geometry of supersymmetric partition functions
Guido Festuccia
(Niels Bohr Inst.)
Abstract:
I will consider supersymmetric field theories on compact manifolds M and obtain constraints on the dependence of their partition functions Z_M on the geometry of M. For N=1 theories with a U(1) R symmetry in four dimensions, M must be a complex manifold with a Hermitian metric. I will show how to describe the theory in terms of twisted variables that make easy to analyze the dependence of Z_M on the parameters entering the Lagrangian. I will also show that Z_M is "almost" topological: Z_M is independent of the Hermitian metric and depends holomorphically on the complex structure moduli.
I will consider supersymmetric field theories on compact manifolds M and obtain constraints on the dependence of their partition functions Z_M on the geometry of M. For N=1 theories with a U(1) R symmetry in four dimensions, M must be a complex manifold with a Hermitian metric. I will show how to describe the theory in terms of twisted variables that make easy to analyze the dependence of Z_M on the parameters entering the Lagrangian. I will also show that Z_M is "almost" topological: Z_M is independent of the Hermitian metric and depends holomorphically on the complex structure moduli.
Posted by: IC
April 2014
Wed
30 Apr 2014
Resurgent Analysis in Quantum Theories: Perturbative Theory and Beyond
Ines Aniceto
(Lisbon)
Abstract:
In order to study the weakly coupled regime of some given quantum theory we often make use of perturbative expansions of the physical quantities of interest. But such expansions are often divergent, with zero radius of convergence, and defined only as asymptotic series. In fact, this divergence is connected to the existence of nonperturbative contributions, i.e. instanton effects that cannot be simply captured by a perturbative analysis. The theory of resurgence is a mathematical tool which allows us to effectively study this connection and its consequences. Moreover, it allows us to construct a full non-perturbative solution from perturbative data. In this talk, I will review the essential role of resurgence theory in the description of the analytic solution behind the asymptotic series. I will then relate resurgence to the so-called Stokes phenomena and phase transitions using a simple example, and will further discuss some major applications of this construction.
In order to study the weakly coupled regime of some given quantum theory we often make use of perturbative expansions of the physical quantities of interest. But such expansions are often divergent, with zero radius of convergence, and defined only as asymptotic series. In fact, this divergence is connected to the existence of nonperturbative contributions, i.e. instanton effects that cannot be simply captured by a perturbative analysis. The theory of resurgence is a mathematical tool which allows us to effectively study this connection and its consequences. Moreover, it allows us to construct a full non-perturbative solution from perturbative data. In this talk, I will review the essential role of resurgence theory in the description of the analytic solution behind the asymptotic series. I will then relate resurgence to the so-called Stokes phenomena and phase transitions using a simple example, and will further discuss some major applications of this construction.
Posted by: QMW
Thu
24 Apr 2014
Eta-deformed AdS5 x S5
Sergey Frolov
(Trinity College, Dublin)
Abstract:
We determine the bosonic part of the superstring sigma model Lagrangian on eta-deformed AdS_5 x S^5, and use it to compute the perturbative world-sheet scattering matrix of bosonic particles of the model. We then compare it with the large string tension limit of the q-deformed S-matrix and find exact agreement. We comment on the structure of the RR sector of the type IIB SUGRA background.
We determine the bosonic part of the superstring sigma model Lagrangian on eta-deformed AdS_5 x S^5, and use it to compute the perturbative world-sheet scattering matrix of bosonic particles of the model. We then compare it with the large string tension limit of the q-deformed S-matrix and find exact agreement. We comment on the structure of the RR sector of the type IIB SUGRA background.
Posted by: IC
Wed
23 Apr 2014
SUSY model building for a 126 GeV Higgs
Moritz Mcgarrie
(DESY)
Abstract:
This talk will explore two possible models which can achieve the correct Higgs mass and still allow for sparticles accessible to the LHC's reach. In the first example we built two tailor made spectrum generators to analyse a Higgs extension (non decoupled D-terms) of the MSSM, based on quiver gauge theories. We then explore the LHC & ILC's capability to determine their effect through their enhancement of Higgs branching ratios with respect to the Standard Model. In the second model, we use the NMSSM to obtain the correct Higgs mass and then explore flavour-gauge mediation to obtain light 3rd generation squarks, whilst keeping the 1st and 2nd generation above exclusions. Both models are also realisable through magnetic SQCD. I will hopefully also discuss further avenues for model building opportunities in the context of Natural SUSY.
This talk will explore two possible models which can achieve the correct Higgs mass and still allow for sparticles accessible to the LHC's reach. In the first example we built two tailor made spectrum generators to analyse a Higgs extension (non decoupled D-terms) of the MSSM, based on quiver gauge theories. We then explore the LHC & ILC's capability to determine their effect through their enhancement of Higgs branching ratios with respect to the Standard Model. In the second model, we use the NMSSM to obtain the correct Higgs mass and then explore flavour-gauge mediation to obtain light 3rd generation squarks, whilst keeping the 1st and 2nd generation above exclusions. Both models are also realisable through magnetic SQCD. I will hopefully also discuss further avenues for model building opportunities in the context of Natural SUSY.
Posted by: QMW
Thu
17 Apr 2014
The geometry of on-shell diagrams
Alberto Mariotti
(Durham University)
Abstract:
I will review the connection between on-shell diagram formulation of N=4 scattering amplitudes,
the Grassmannian, and N=1 bipartite field theories.
I will then perform a detailed investigation of the combinatorial and geometric objects associated
to bipartite graphs, focusing on toric geometry and on the stratification of the Grassmannian.
I will show how this description extends to the non-planar case, providing powerful tools to
study the on-shell formulation of scattering amplitudes beyond the planar limit.
I will review the connection between on-shell diagram formulation of N=4 scattering amplitudes,
the Grassmannian, and N=1 bipartite field theories.
I will then perform a detailed investigation of the combinatorial and geometric objects associated
to bipartite graphs, focusing on toric geometry and on the stratification of the Grassmannian.
I will show how this description extends to the non-planar case, providing powerful tools to
study the on-shell formulation of scattering amplitudes beyond the planar limit.
Posted by: QMW
Thu
10 Apr 2014
Holographic accelerating heavy quark
Gordon Semenoff
(British Columbia U.)
Abstract:
A formula for the interaction energy of an eternally accelerated heavy quark-antiquark pair in N=4 Yang-Mills theory is derived and its implications are discussed, both in the context of strongly coupled Yang-Mills theory and in its dual, the IIB string theory.
A formula for the interaction energy of an eternally accelerated heavy quark-antiquark pair in N=4 Yang-Mills theory is derived and its implications are discussed, both in the context of strongly coupled Yang-Mills theory and in its dual, the IIB string theory.
Posted by: QMW
Wed
9 Apr 2014
Infinite chiral symmetry in four dimensions
Balt van Rees
(CERN)
Abstract:
We describe a new correspondence between four-dimensional conformal field theories with extended supersymmetry and two-dimensional chiral algebras. The meromorphic correlators of the chiral algebra compute correlators in a protected sector of the four-dimensional theory. Infinite chiral symmetry has far-reaching consequences for the spectral data, correlation functions, and central charges of any four-dimensional theory with N=2 superconformal symmetry.
We describe a new correspondence between four-dimensional conformal field theories with extended supersymmetry and two-dimensional chiral algebras. The meromorphic correlators of the chiral algebra compute correlators in a protected sector of the four-dimensional theory. Infinite chiral symmetry has far-reaching consequences for the spectral data, correlation functions, and central charges of any four-dimensional theory with N=2 superconformal symmetry.
Posted by: IC
Thu
3 Apr 2014
The topology of giant gravitons from meromorphic functions
Andrea Prinsloo
(Surrey U.)
Abstract:
I will present a systematic study of the topology of Mikhailov's quarter and eighth-BPS giant gravitons in AdS_5 x S^5. These D3-branes are rigidly rotating 3-manifolds embedded into the 5-sphere compact space, which are dual to long, gauge-invariant, quarter and eighth-BPS operators in N=4 SYM theory by the AdS/CFT correspondence. How the topology is encoded in these operators remains an open question.
I will present a systematic study of the topology of Mikhailov's quarter and eighth-BPS giant gravitons in AdS_5 x S^5. These D3-branes are rigidly rotating 3-manifolds embedded into the 5-sphere compact space, which are dual to long, gauge-invariant, quarter and eighth-BPS operators in N=4 SYM theory by the AdS/CFT correspondence. How the topology is encoded in these operators remains an open question.
Posted by: QMW
Wed
2 Apr 2014
Scale vs conformal invariance in four dimensions
Kostas Skenderis
(STAG, Southampton U.)
Abstract:
I will discuss the question of whether four dimensional scale invariant unitary quantum field theories are actually conformally invariant.
I will present a complete analysis of possible scale anomalies in correlation functions of the trace of the stress-energy tensor in such theories and discuss recent attempts to show that scale invariance implies conformal invariance.
I will discuss the question of whether four dimensional scale invariant unitary quantum field theories are actually conformally invariant.
I will present a complete analysis of possible scale anomalies in correlation functions of the trace of the stress-energy tensor in such theories and discuss recent attempts to show that scale invariance implies conformal invariance.
Posted by: IC
Wed
2 Apr 2014
New Insight into CFTs from the Bootstrap Mechanism
Ferdinando Gliozzi
(INFN, Torino)
Abstract:
I describe a general method implementing the crossing symmetry constraints in a large class of CFTs. Starting with
the knowledge of the fusion rules of scalar operators,
this method can generate systematically the scaling dimensions of the
low-lying primaries of the theory. Its application to the Yang -Lee
edge singularity for \(2\le D \le 6\) and to the 3d critical Ising model
gives rather accurate results and allows to estimate several new critical
exponents
I describe a general method implementing the crossing symmetry constraints in a large class of CFTs. Starting with
the knowledge of the fusion rules of scalar operators,
this method can generate systematically the scaling dimensions of the
low-lying primaries of the theory. Its application to the Yang -Lee
edge singularity for \(2\le D \le 6\) and to the 3d critical Ising model
gives rather accurate results and allows to estimate several new critical
exponents
Posted by: QMW
Tue
1 Apr 2014
T-duality and scattering of stringy states
Jnanadeva Maharana
(Institute of Physics, Bhubaneswar (visiting Prof at IC))
Abstract:
A brief review will recapitulate some of the essential features of T-duality symmetry in string theory. A proposal will be presented to show how a scattering amplitude of some string excitations could be related to another amplitude by T-duality transformation for a class of stringy states. This is considered in a simple scenario. Some illustrative examples will be presented as application of the proposal.
A brief review will recapitulate some of the essential features of T-duality symmetry in string theory. A proposal will be presented to show how a scattering amplitude of some string excitations could be related to another amplitude by T-duality transformation for a class of stringy states. This is considered in a simple scenario. Some illustrative examples will be presented as application of the proposal.
Posted by: IC
March 2014
Mon
31 Mar 2014
Matrix Dynamics and Black Holes
David Berenstein
(UCSB)
Thu
27 Mar 2014
Towards an Effective Field Theory of Structure Formation
Valentin Assassi
(Cambridge)
Abstract:
Over the next decade, large scale structure (LSS) surveys will play an increasingly important role in the measurement of cosmological parameters and as a probe of initial conditions. Relating the observed galaxies to the physics of the early universe requires a good understanding of several late-time sources of non-linear effects. In this talk, I will explain how, looking at large scales, effective field theory (EFT) offers a natural framework to deal with these non-linearities. After reviewing the recently developed effective field theory of large scale structure, I will explain how the halo bias model - a model relating the density of dark matter halos to the underlying dark matter density - can be understood in the context of EFT. In the final part of the talk, I will show explicit computations of halo statistics and discuss their observational consequences.
Over the next decade, large scale structure (LSS) surveys will play an increasingly important role in the measurement of cosmological parameters and as a probe of initial conditions. Relating the observed galaxies to the physics of the early universe requires a good understanding of several late-time sources of non-linear effects. In this talk, I will explain how, looking at large scales, effective field theory (EFT) offers a natural framework to deal with these non-linearities. After reviewing the recently developed effective field theory of large scale structure, I will explain how the halo bias model - a model relating the density of dark matter halos to the underlying dark matter density - can be understood in the context of EFT. In the final part of the talk, I will show explicit computations of halo statistics and discuss their observational consequences.
Posted by: QMW
Wed
26 Mar 2014
Exact tachyon spectrum in AdS/CFT
📍 London
Ryo Suzuki
(Oxford)
Abstract:
Unstable string states in curved spacetime is not well-understood compared to those in the flat spacetime. We consider potentially tachyonic open string states in AdS_5xS^5 which should correspond to a determinant-like operator in N=4 super Yang-Mills by the AdS/CFT correspondence. Its conformal dimension is studied using integrability and perturbative methods in N=4 SYM. By proposing and solving the boundary thermodynamic Bethe ansatz (BTBA) equations, we find an indication that states of N=4 SYM turn into tachyonic at finite coupling where the total energy of the corresponding string becomes zero.
Unstable string states in curved spacetime is not well-understood compared to those in the flat spacetime. We consider potentially tachyonic open string states in AdS_5xS^5 which should correspond to a determinant-like operator in N=4 super Yang-Mills by the AdS/CFT correspondence. Its conformal dimension is studied using integrability and perturbative methods in N=4 SYM. By proposing and solving the boundary thermodynamic Bethe ansatz (BTBA) equations, we find an indication that states of N=4 SYM turn into tachyonic at finite coupling where the total energy of the corresponding string becomes zero.
Posted by: KCL
Wed
26 Mar 2014
BPS solitons and Wilson lines
Kenny Wong
(DAMTP Cambridge)
Abstract:
This talk addresses a basic question about supersymmetric gauge theory: how does a soliton behave in the vicinity of a heavy charged object? The answer to this question is intuitive and geometrical, and can be expressed in terms of a natural connection over the soliton moduli space.
Based on 1309.2644 and 1401.6167 with David Tong.
This talk addresses a basic question about supersymmetric gauge theory: how does a soliton behave in the vicinity of a heavy charged object? The answer to this question is intuitive and geometrical, and can be expressed in terms of a natural connection over the soliton moduli space.
Based on 1309.2644 and 1401.6167 with David Tong.
Posted by: IC
Mon
24 Mar 2014
Lattice Formulations of Supersymmetric Yang-Mills Theories
Anosh Joseph
(DESY)
Abstract:
Certain classes of supersymmetric Yang-Mills (SYM) theories including the well known N=4 SYM, that takes part in the AdS/CFT correspondence, can be formulated on a Euclidean spacetime lattice using the techniques of exact lattice supersymmetry. In this talk I will provide the constructions of such theories and describe how great ideas such as topological field theories, Dirac-Kahler fermions, geometric discretization all come together to create lattice SYM theories that are exact-supersymmetric, gauge-invariant, local and doubler-free on the lattice. Then I move on to discuss the recent lattice constructions of specific classes SYM theories in two dimensions, with matter in various representations.
Certain classes of supersymmetric Yang-Mills (SYM) theories including the well known N=4 SYM, that takes part in the AdS/CFT correspondence, can be formulated on a Euclidean spacetime lattice using the techniques of exact lattice supersymmetry. In this talk I will provide the constructions of such theories and describe how great ideas such as topological field theories, Dirac-Kahler fermions, geometric discretization all come together to create lattice SYM theories that are exact-supersymmetric, gauge-invariant, local and doubler-free on the lattice. Then I move on to discuss the recent lattice constructions of specific classes SYM theories in two dimensions, with matter in various representations.
Posted by: IC
Fri
21 Mar 2014
TBA
Yang-Hui He
(City U.)
Thu
20 Mar 2014
Non-Supersymmetric Brane Configurations, Seiberg Duality and Dynamical Symmetry Breaking
Adi Armoni
(Swansea U.)
Abstract:
In this talk I will consider brane configurations that include NS5 branes, orientifold planes and anti-branes. I will argue that the class of field theories that live on
such brane configurations admit Seiberg duality. Interactions between branes and orientifold planes will be given a field theory interpretation. In particular a certain repulsive interaction will lead to a non-trivial Coleman-Weinberg potential and dynamical symmetry breaking. I will also discuss the case of type 0' strings and chiral symmetry breaking of the form SU(Nf)xSU(Nf)–>SU(Nf) in a QCD-like theory.
In this talk I will consider brane configurations that include NS5 branes, orientifold planes and anti-branes. I will argue that the class of field theories that live on
such brane configurations admit Seiberg duality. Interactions between branes and orientifold planes will be given a field theory interpretation. In particular a certain repulsive interaction will lead to a non-trivial Coleman-Weinberg potential and dynamical symmetry breaking. I will also discuss the case of type 0' strings and chiral symmetry breaking of the form SU(Nf)xSU(Nf)–>SU(Nf) in a QCD-like theory.
Posted by: QMW
Wed
19 Mar 2014
Localisation on three-manifolds
📍 London
Paul Richmond
(Oxford)
Abstract:
In this talk I will discuss the localisation of supersymmetric gauge theories on Riemannian three-manifolds with the topology of a three-sphere. The three-manifold is always equipped with an almost contact structure and an associated Reeb vector field. The partition function depends only on this vector field and has an explicit expression in terms of the double sine function. In addition, I will discuss the possibility of generalising this work to five dimensions.
In this talk I will discuss the localisation of supersymmetric gauge theories on Riemannian three-manifolds with the topology of a three-sphere. The three-manifold is always equipped with an almost contact structure and an associated Reeb vector field. The partition function depends only on this vector field and has an explicit expression in terms of the double sine function. In addition, I will discuss the possibility of generalising this work to five dimensions.
Posted by: KCL
Wed
19 Mar 2014
One loop tests of higher spin AdS/CFT
Simone Giombi
(Princeton)
Abstract:
Higher spin gravity theories in Anti-de Sitter space have been conjectured to be holographically dual to conformal field theories with vector-like matter fields: in the simplest version of the duality, these are just free CFT's of N-component massless scalars or fermions. After reviewing these conjectures, I will discuss recent new tests of the duality based on comparing the bulk and boundary partition functions. In particular, I will show that the sum over one loop free energies of the infinite set of massless higher spin gauge fields in AdS_{d+1} is precisely consistent with the form of the O(N^0) term in the partition function of the CFT on S^d and S^1xS^{d-1}.
Higher spin gravity theories in Anti-de Sitter space have been conjectured to be holographically dual to conformal field theories with vector-like matter fields: in the simplest version of the duality, these are just free CFT's of N-component massless scalars or fermions. After reviewing these conjectures, I will discuss recent new tests of the duality based on comparing the bulk and boundary partition functions. In particular, I will show that the sum over one loop free energies of the infinite set of massless higher spin gauge fields in AdS_{d+1} is precisely consistent with the form of the O(N^0) term in the partition function of the CFT on S^d and S^1xS^{d-1}.
Posted by: IC
Tue
18 Mar 2014
String Scattering amplitudes, Feynman diagrams and M-Theory
Michael B. Green
(DAMTP Cambridge)
Abstract:
This talk will review perturbative and non-perturbative properties of string theory scattering amplitudes with particular emphasis on the constraints imposed by duality with M-theory on their low energy action.
This talk will review perturbative and non-perturbative properties of string theory scattering amplitudes with particular emphasis on the constraints imposed by duality with M-theory on their low energy action.
Posted by: IC
Mon
17 Mar 2014
Scaling relations in quantum quench: holography and beyond
Sumit Das
(Kentucky)
Wed
12 Mar 2014
Anomalies and the thermodynamic partition function
Amos Yarom
(Technion, Haifa)
Abstract:
Theories with anomalies exhibit unusual thermodynamic and hydrodynamic behavior. This behavior may be captured entirely by constructing a "thermal" anomaly polynomial which encodes the solution to the Wess-Zumino consistency condition and an additional condition (consistency with the Euclidian vacuum) which the thermodynamic partition function must satisfy. Using the thermodynamic partition function, the role of the anomaly in hydrodynamics can be traced to the coefficients of certain Chern-Simons terms on the base manifold over which the thermal circle is fibered.
Theories with anomalies exhibit unusual thermodynamic and hydrodynamic behavior. This behavior may be captured entirely by constructing a "thermal" anomaly polynomial which encodes the solution to the Wess-Zumino consistency condition and an additional condition (consistency with the Euclidian vacuum) which the thermodynamic partition function must satisfy. Using the thermodynamic partition function, the role of the anomaly in hydrodynamics can be traced to the coefficients of certain Chern-Simons terms on the base manifold over which the thermal circle is fibered.
Posted by: IC
Wed
12 Mar 2014
Elliptic genera, mock modular forms and applications
Jan Troost
(ENS Paris)
Abstract:
We discuss elliptic genera of supersymmetric two-dimensional conformal field theories with continuous spectra. We argue that they consist of a mock modular term, and a non-holomorphic modular completion. We illustrate the general arguments with a large class of examples, computed using conformal field theory, string theory and localization techniques. We discuss applications, amongst others to black hole physics.
We discuss elliptic genera of supersymmetric two-dimensional conformal field theories with continuous spectra. We argue that they consist of a mock modular term, and a non-holomorphic modular completion. We illustrate the general arguments with a large class of examples, computed using conformal field theory, string theory and localization techniques. We discuss applications, amongst others to black hole physics.
Posted by: IC
Thu
6 Mar 2014
TBA
Dimitri Skliros
(Nottingham U.)
Wed
5 Mar 2014
Entanglement in higher spin theories
📍 London
Eric Perlmutter
(DAMTP Cambridge)
Abstract:
There has been phenomenal recent progress in computing CFT entanglement and Renyi entropies, holographically and otherwise. We extend these investigations to the higher spin regime – where sensible notions of geometry are sorely lacking – by computing ground state Renyi entropies in certain classes of holographic CFTs with higher spin symmetry. Our calculations are performed at both classical and one-loop level, from gravity and CFT. Along the way, we establish some new general results about Renyi entropy in any CFT, higher spin symmetry aside.
There has been phenomenal recent progress in computing CFT entanglement and Renyi entropies, holographically and otherwise. We extend these investigations to the higher spin regime – where sensible notions of geometry are sorely lacking – by computing ground state Renyi entropies in certain classes of holographic CFTs with higher spin symmetry. Our calculations are performed at both classical and one-loop level, from gravity and CFT. Along the way, we establish some new general results about Renyi entropy in any CFT, higher spin symmetry aside.
Posted by: KCL
Wed
5 Mar 2014
Flux-tube methods for scattering amplitudes in planar N=4 SYM theory
Benjamin Basso
(ENS Paris)
Abstract:
In this talk, I will explain how to compute gluon scattering amplitudes in planar N=4 Super-Yang-Mills theory using the flux tube (OPE) picture. The latter, which builds on the duality with light-like Wilson loops, provides a description of scattering amplitudes in terms of excitations evolving on a two-dimensional background. Exploiting the remarkable integrable structures of this background, one can formulate scattering amplitudes, at
any values of the 't Hooft coupling, as an expansion around the multi-collinear (a.k.a. OPE) limit. I shall report on recent progress made in this direction and speculate on its possible application to the study of scattering amplitudes in the multi-Regge kinematics.
In this talk, I will explain how to compute gluon scattering amplitudes in planar N=4 Super-Yang-Mills theory using the flux tube (OPE) picture. The latter, which builds on the duality with light-like Wilson loops, provides a description of scattering amplitudes in terms of excitations evolving on a two-dimensional background. Exploiting the remarkable integrable structures of this background, one can formulate scattering amplitudes, at
any values of the 't Hooft coupling, as an expansion around the multi-collinear (a.k.a. OPE) limit. I shall report on recent progress made in this direction and speculate on its possible application to the study of scattering amplitudes in the multi-Regge kinematics.
Posted by: IC
February 2014
Thu
27 Feb 2014
Aspects of 5d gauge theories
Diego Rodriguez-Gomez
(Oviedo U.)
Abstract:
In this talk I will review recent progress in understanding aspects of 5d gauge theories. Under certain circumstances these can be at fixed points admitting a large N limit, whose gravity dual we will discuss. Such gravity dual suggests a yet more general class of quiver-type fixed point theories which can sometimes be understood in terms of S-duality. To this matter the braneweb construction of the theories will prove very helpful, yielding new insights which we will test using the 5d superconformal index.
In this talk I will review recent progress in understanding aspects of 5d gauge theories. Under certain circumstances these can be at fixed points admitting a large N limit, whose gravity dual we will discuss. Such gravity dual suggests a yet more general class of quiver-type fixed point theories which can sometimes be understood in terms of S-duality. To this matter the braneweb construction of the theories will prove very helpful, yielding new insights which we will test using the 5d superconformal index.
Posted by: QMW
Wed
26 Feb 2014
Wick rotation and the positivity of energy in quantum field theory
📍 London
Graeme Segal
(Oxford)
Abstract:
The positivity of energy in quantum field theory is traditionally but not altogether clearly encoded in the possibility of ‘Wick rotation’ – the analytic continuation of various observable quantities to ‘imaginary time’. My talk, an account of joint work with Maxim Kontsevich, will describe a somewhat different point of view on this. I shall motivate the definition of a specific infinite-dimensional domain of complex-valued metrics on a smooth manifold which is a complexification of the usual space of real Riemannian metrics, but has the Lorentzian metrics on its boundary. The positivity of energy is then encoded in the fact that the theory is the boundary value of a holomorphic theory defined for space-time manifolds with complex metrics belonging to the domain. Questions of the unitarity of field theory in a curved space-time are thereby related to familiar phenomena in representation theory.
The positivity of energy in quantum field theory is traditionally but not altogether clearly encoded in the possibility of ‘Wick rotation’ – the analytic continuation of various observable quantities to ‘imaginary time’. My talk, an account of joint work with Maxim Kontsevich, will describe a somewhat different point of view on this. I shall motivate the definition of a specific infinite-dimensional domain of complex-valued metrics on a smooth manifold which is a complexification of the usual space of real Riemannian metrics, but has the Lorentzian metrics on its boundary. The positivity of energy is then encoded in the fact that the theory is the boundary value of a holomorphic theory defined for space-time manifolds with complex metrics belonging to the domain. Questions of the unitarity of field theory in a curved space-time are thereby related to familiar phenomena in representation theory.
Posted by: KCL
Wed
26 Feb 2014
Aspects of 5d gauge theories
Diego Rodriguez-Gomez
(Oviedo)
Abstract:
In this talk I will review recent progress in understanding aspects of 5d gauge theories. Under certain circumstances these can be at fixed points admitting a large N limit, whose gravity dual we will discuss. Such gravity dual suggests a yet more general class of quiver-type fixed point theories which can sometimes be understood in terms of S-duality. To this matter the braneweb construction of the theories will prove very helpful, yielding new insights which we will test using the 5d superconformal index.
In this talk I will review recent progress in understanding aspects of 5d gauge theories. Under certain circumstances these can be at fixed points admitting a large N limit, whose gravity dual we will discuss. Such gravity dual suggests a yet more general class of quiver-type fixed point theories which can sometimes be understood in terms of S-duality. To this matter the braneweb construction of the theories will prove very helpful, yielding new insights which we will test using the 5d superconformal index.
Posted by: IC
Thu
20 Feb 2014
Integrable q-deformation of the AdS5 x S5 superstring
Marc Magro
(ENS Lyon)
Abstract:
I will first review the algebraic structure related to the classical integrability of sigma models at the hamiltonian level. I will then show how this hamiltonian perspective enables to construct an integrable q-deformation of the AdS5 x S5 superstring action.
I will first review the algebraic structure related to the classical integrability of sigma models at the hamiltonian level. I will then show how this hamiltonian perspective enables to construct an integrable q-deformation of the AdS5 x S5 superstring action.
Posted by: IC
Wed
19 Feb 2014
Seminar Cancelled
📍 London
Fedor Smirnov
(LPTHE Paris)
Abstract:
Using the fermionic basis we conjecture explicit formulae
for the one-point functions in the sinh-Gordon model on a cylinder at finite temperature). The conjecture is checked against known results.
Using the fermionic basis we conjecture explicit formulae
for the one-point functions in the sinh-Gordon model on a cylinder at finite temperature). The conjecture is checked against known results.
Posted by: KCL
Wed
19 Feb 2014
Higher-spin symmetry in AdS and CFT
Eugene Skvortsov
(AEI Potsdam)
Abstract:
I will discuss the implications of extended symmetries in higher dimensional CFT's and show that the algebra they generate, the higher-spin algebra, is unique (which extends Maldacena-Zhiboedov results). As an infinite-dimensional extension of conformal symmetries higher-spin algebras can be used to restrict correlation functions and I will present an explicit formula that computes all correlators in unbroken Vasiliev higher-spin theory.
I will discuss the implications of extended symmetries in higher dimensional CFT's and show that the algebra they generate, the higher-spin algebra, is unique (which extends Maldacena-Zhiboedov results). As an infinite-dimensional extension of conformal symmetries higher-spin algebras can be used to restrict correlation functions and I will present an explicit formula that computes all correlators in unbroken Vasiliev higher-spin theory.
Posted by: IC
Wed
12 Feb 2014
Holographic entanglement entropy in AdS_3/CFT_2
Alejandra Castro
(Amsterdam)
Wed
12 Feb 2014
Towards Kerr from Warped Conformal Field Theory
Diego Hofman
(Amsterdam)
Wed
5 Feb 2014
Exceptional geometry, gauged supergravity and the tensor hierarchy
📍 London
Mariana Grana
(IPhT Saclay)
Abstract:
Exceptional generalised geometry (or exceptional field theory) is an extension of generalised complex geometry (or double field theory) "geometrising" all degrees of freedom of 11d or type II supergravity. Concentrating on the case in which the 11d tangent space is split into four and seven dimensional spaces, we will discuss the geometry and gauge structure of these exceptional theories. We will show how closure of the "exceptional Lie algebra" requires adding a tower of four-dimensional p-form fields, known in the 4d gauged supergravity language as the tensor hierarchy. This indicates the existence of an underlying structure compatible with the E_{11} construction.
Exceptional generalised geometry (or exceptional field theory) is an extension of generalised complex geometry (or double field theory) "geometrising" all degrees of freedom of 11d or type II supergravity. Concentrating on the case in which the 11d tangent space is split into four and seven dimensional spaces, we will discuss the geometry and gauge structure of these exceptional theories. We will show how closure of the "exceptional Lie algebra" requires adding a tower of four-dimensional p-form fields, known in the 4d gauged supergravity language as the tensor hierarchy. This indicates the existence of an underlying structure compatible with the E_{11} construction.
Posted by: KCL
Wed
5 Feb 2014
A Holographic Model of the Kondo Effect
Andy O'Bannon
(Oxford)
Abstract:
The Kondo effect occurs in metals doped with magnetic impurities: in the ground state the electrons form a screening cloud around each impurity, leading to dramatic changes in the thermodynamic and transport properties of the metal. Although the single-impurity Kondo effect is considered a solved problem, many questions remain, especially about the fate of the Kondo effect in the presence of multiple impurities. In particular, for a sufficiently dense concentration of impurities, a competition between the Kondo effect and inter-impurity interactions can lead to quantum criticality and non-Fermi liquid behavior, which remains poorly understood. In this talk I will present a model of the single-impurity Kondo effect based on holography, also known as gauge-gravity duality or the AdS/CFT correspondence, which may serve as a foundation for a new approach to the multiple-impurity system.
The Kondo effect occurs in metals doped with magnetic impurities: in the ground state the electrons form a screening cloud around each impurity, leading to dramatic changes in the thermodynamic and transport properties of the metal. Although the single-impurity Kondo effect is considered a solved problem, many questions remain, especially about the fate of the Kondo effect in the presence of multiple impurities. In particular, for a sufficiently dense concentration of impurities, a competition between the Kondo effect and inter-impurity interactions can lead to quantum criticality and non-Fermi liquid behavior, which remains poorly understood. In this talk I will present a model of the single-impurity Kondo effect based on holography, also known as gauge-gravity duality or the AdS/CFT correspondence, which may serve as a foundation for a new approach to the multiple-impurity system.
Posted by: IC
January 2014
Wed
29 Jan 2014
Integrabilty and STU supergravity
📍 London
Axel Kleinschmidt
(AEI Potsdam)
Abstract:
I will review the known integrable structures of (super-)gravity in the presence of a sufficient number of Killing vectors and how they can be used to generate new solutions. The associated inverse scattering techniques have been widely applied to four-dimensional Einstein gravity, starting with the work of Belinski and Zakharov, but their generalisation to other gravity systems poses some problems. I will discuss progress for the case of STU supergravity by exploiting the underlying group theory.
I will review the known integrable structures of (super-)gravity in the presence of a sufficient number of Killing vectors and how they can be used to generate new solutions. The associated inverse scattering techniques have been widely applied to four-dimensional Einstein gravity, starting with the work of Belinski and Zakharov, but their generalisation to other gravity systems poses some problems. I will discuss progress for the case of STU supergravity by exploiting the underlying group theory.
Posted by: KCL
Wed
29 Jan 2014
Exact results for 5D Yang-Mills theory on toric Sasaki-Einstein manifolds
Maxim Zabzine
(Uppsala)
Abstract:
I will review the localisation of 5D supersymmetric Yang-Mills theory on the toric Sasaki-Einstein manifolds. As main examples, the case of sphere and Y^{p,q} spaces will be considered. The large N-limit and factorisation properties of exact partition function will discussed.
I will review the localisation of 5D supersymmetric Yang-Mills theory on the toric Sasaki-Einstein manifolds. As main examples, the case of sphere and Y^{p,q} spaces will be considered. The large N-limit and factorisation properties of exact partition function will discussed.
Posted by: IC
Thu
23 Jan 2014
Amplitudes of HIggsed ABJM
Donovan Young
(QMUL)
Wed
22 Jan 2014
BPS black holes in AdS_4 and their CFT duals
📍 London
Kiril Hristov
(Milano Bicocca)
Abstract:
The microscopic description of the 4 dimensional supersymmetric (or BPS) black holes in flat space has already been well understood via the AdS/CFT correspondence on the black hole horizon. In this talk I address the similar problem of finding the dual description for the static BPS black holes in AdS_4 embeddable in M-theory. The gravity picture of an interpolation between asymptotic AdS_4 and AdS_2xS^2 on the horizon can be understood as a renormalization group (RG) flow between a 3d and a 1d superconformal field theory. I discuss in some detail both the gravity and the field theory side, providing evidence for their match. At the end I present a proposal for the 1d CFT states that make up the black hole entropy.
The microscopic description of the 4 dimensional supersymmetric (or BPS) black holes in flat space has already been well understood via the AdS/CFT correspondence on the black hole horizon. In this talk I address the similar problem of finding the dual description for the static BPS black holes in AdS_4 embeddable in M-theory. The gravity picture of an interpolation between asymptotic AdS_4 and AdS_2xS^2 on the horizon can be understood as a renormalization group (RG) flow between a 3d and a 1d superconformal field theory. I discuss in some detail both the gravity and the field theory side, providing evidence for their match. At the end I present a proposal for the 1d CFT states that make up the black hole entropy.
Posted by: KCL
Wed
22 Jan 2014
TBA
Dimitri Polyakov
(Seoul)
Wed
22 Jan 2014
Polygon seminar: Black Hole Basics
Malcolm Perry
(Cambridge)
Mon
20 Jan 2014
Tropical Amplitudes
Piotr Tourkine
(CEA Saclay)
Abstract:
A systematic understanding of the low energy limit of string theory scattering amplitudes is essential for conceptual and practical reasons. In this talk, I shall report on a recent work where this limit has been analyzed using tropical geometry. Our result is that the field theory amplitudes arising in the low energy limit of string theory are written in a very compact form as integrals over a single object, the tropical moduli space. This picture provides a general framework where the different aspects of the low energy limit of string theory scattering amplitudes are systematically encompassed; the Feynman graphs structure and the ultraviolet regulation mechanism. I shall then give examples of application of the formalism, in particular at genus two, and discuss open issues.
No knowledge of tropical geometry will be assumed and the topic shall be introduced during the talk.
A systematic understanding of the low energy limit of string theory scattering amplitudes is essential for conceptual and practical reasons. In this talk, I shall report on a recent work where this limit has been analyzed using tropical geometry. Our result is that the field theory amplitudes arising in the low energy limit of string theory are written in a very compact form as integrals over a single object, the tropical moduli space. This picture provides a general framework where the different aspects of the low energy limit of string theory scattering amplitudes are systematically encompassed; the Feynman graphs structure and the ultraviolet regulation mechanism. I shall then give examples of application of the formalism, in particular at genus two, and discuss open issues.
No knowledge of tropical geometry will be assumed and the topic shall be introduced during the talk.
Posted by: IC
Mon
20 Jan 2014
Graduate lecture: Higher Spins , Holography and String Theory
Dimitri Polyakov
(Seoul)
Thu
16 Jan 2014
Non-perturbative bounds for structure constants
Agnese Bissi
(Oxford)
Tue
14 Jan 2014
Graduate lecture: Higher Spin Gauge Theories in various backgrounds (general introduction)
Dimitri Polyakov
(Seoul)