Programme

Titles and abstracts

Changrim Ahn, (Seoul, EWHA)

Title: 3-point functions of finite-size Giant Magnons

Abstract: We report semiclassical 3-point correlation functions of a light dilaton mode and two (dyonic) giant magnon string states with finite-size J both on R x S^3 and on gamma-deformed Lunin-Maldacena background. We show consistency of our result by relating them to conformal dimensions or E-J.

Martin Ammon, (UCLA)

Title: Gauge/Gravity Duality applied to Condensed matter systems

Abstract: In this talk I will review recent progress in gauge/gravity duality towards the description of strongly coupled systems near quantum critical points. I will focus on an explicit, string theory inspired realization of gauge/gravity dualities in terms of D-branes. In these models it is possible to find superconducting instabilites as well as (non)-Fermi liquids. I will comment on new universal behavior and compare to effects at weak coupling.

Gleb Arutyunov, (Utrecht Univ.)

Title: The mirror TBA

Abstract: I review some aspects concerning the construction of the Thermodynamic Bethe Ansatz equations describing the spectrum of the AdS_5 x S^5 superstring.

Dongsu Bak, (Seoul Univ.)

Title: Phase Transitions in the U(1) Charged Sector of ABJM Theory

Abstract: We consider the U(1) charged sector of ABJM theory at finite temperature, which corresponds to the Reissner-Nordstrom AdS black hole in the dual type IIA supergravity description. Including back-reaction to the bulk geometry, We shall show that phase transitions occur to a broken phase where SU(4) R-symmetry of the field theory is broken spontaneously by the condensation of dimension one or two operators. We demonstrate both numerically and analytically that the relevant critical exponents for the dimension one operator agree precisely with those of mean field theory in the strongly coupled regime of the large N planar limit.

János Balog, (Budapest, KFKI)

Title: Mirror TBA equations from Y-system and discontinuity relations

Abstract: Using the recently proposed set of discontinuity relations we translate the AdS/CFT Y-system to TBA integral equations and quantization conditions for a large subset of excited states from the sl(2) sector of the $AdS_5 \\times S^5$ string sigma-model. Our derivation provides an analytic proof of the fact that the exact Bethe equations reduce to the Beisert-Staudacher equations in the asymptotic limit. We also construct the corresponding T-system and show that in the language of T-functions the energy formula reduces to a single term which depends on a single T-function.

Sophia K. Domokos, (Weizmann Inst.)

Title: Extending the framework of AdS/QCD: new mesons and interactions

Abstract: Though existing models of AdS/QCD have quite successfully described certain states of the low-lying meson spectrum, they have largely neglected b1-type axial vector mesons, whose masses are of the same order as the much-studied rho and a1. I will describe a natural extension of the \"hard wall\" model of AdS/QCD, which not only incorporates these ignored states, but also provides an additional tower of rho-like mesons which improves agreement with the masses of radial rho-like excitations.

Johanna Erdmenger, (Munich, MPI)

Title: Holographic p-wave superconductors

Abstract: Recently, considerable progress has been achieved in using gauge/gravity duality for describing strongly coupled systems of relevance for condensed matter physics. In this context, I consider both top-down approaches and bottom-up approaches to holographic superconductors where the order parameter has p-wave symmetry. In the top-down approaches, the holographic superconductors are realized in a probe brane construction involving a probe of two D-branes at finite isospin density. The dual field theory is known explicitly. We obtain the thermodynamics and the Fermi surface for these systems. Moreover, we consider bottom-up approaches for p-wave superconductors in which we study the back-reaction of the required SU(2) gauge field on the geometry. We find the phase diagram. A particularly interesting feature of this model is that the shear viscosity over entropy ratio displays non-universal behaviour, it is temperature-dependent at leading order in N and lambda.

Carlo Ewerz, (Heidelberg)

Title: Screening in Strongly Coupled Plasmas from AdS/CFT:

Abstract: We use the gauge/gravity correspondence to study the screening of a heavy quark-antiquark pair in various strongly coupled plasmas. We consider the dependence of the screening distance on the velocity and the orientation of the pair in the plasma. The value of the screening distance in N=4$ SYM is found to be a minimum in a large class of theories. We further discuss the behaviour of the running coupling in these theories.

Tony Gherghetta, (Melbourne Univ.)

Title: Generating a Little Hierarchy from Accidental SUSY

Abstract: An emergent or accidental supersymmetry is used to address the little hierarchy problem in Randall-Sundrum models by naturally generating a hierarchy between the IR scale and the electroweak scale. Supersymmetry is broken on the UV brane which triggers the stabilization of the warped extra dimension at an IR scale of order 10 TeV. This causes the first two sparticle generations to decouple, thereby avoiding the supersymmetric flavour and CP problems, while an accidental R-symmetry protects the gaugino mass. The resulting low-energy sparticle spectrum consists of stops, gauginos and Higgsinos which are sufficient to stabilize the little hierarchy between the IR scale and the electroweak scale. Introducing a singlet Higgs field on the IR brane, ameliorates the supersymmetric little hierarchy problem, and allows Higgs masses up to 300 GeV.

Floriana Giannuzzi, (Bari)

Title: Spectral functions at finite temperature and density in the Soft Wall model of Holographic QCD

Abstract: The spectral functions of vector and scalar mesons are computed in the Soft Wall model of Holographic QCD at different temperatures and densities in the AdS space with a black hole. The behaviour of the spectra is shown in the parameter space.

Romuald Janik, (Krakow, Jagiellonian Univ.)

Title: Strongly coupled plasma - from nonequillibrium to hydrodynamics through AdS/CFT

Abstract: In this talk I review the recent work on the application of the AdS/CFT correspondence to the study of the evolution of boost invariant plasma starting from various initial conditions. The main goal of this study is to isolate the key features of the transition from nonequilibrium to hydrodynamic behaviour. This is a direct N=4 SYM analog of the early thermalization puzzle of quark-gluon plasma produced in relativistic heavy-ion collisions.

Antal Jevicki, (Brown Univ.)

Title: Higher Spin ADS Gravity from Conformal Field Theory : A Constructive Approach

Abstract: We plan to review recent work on the Higher Spin Gravity /Vector Model CFT Correspondence. A constructive approach relating Higher Spin AdS fields to fields of the Large N vector model will be presented with emphasis on reconstruction of AdS space-time and of bulk gravity degrees of freedom. The holographic RG method will also be commented upon.

Gregory Korchemsky, (Paris, Saclay, IPhT)

Title: Dualities for scattering amplitudes in maximally supersymmetric Yang-Mills theory

Abstract: I will review a recent progress in computing scattering amplitudes in N=4 SYM theory and explain the recently found duality between gluon scattering amplitudes and correlation functions of half-BPS protected operators in the limit where the positions of the adjacent operators become light-like separated.

Tomasz Lukowski, (Berlin)

Title: Spin chains in the AdS/CFT correspondence

Abstract: I will present a novel construction of Baxter operators for spin chains with given representation in the quantum space. As a special case It furnishes to find an alternative solution of the one-loop spectral problem of the AdS/CFT correspondence. This construction gives also hope for better understanding of the full spectrum of this theory.

Márk Mezei, (MIT)

Title: Finite density dynamics from holography

Abstract: Holography provides an efficient new way of studying strongly interacting systems at finite density. In the dual gravity setup we generically encounter an AdS$_2$ factor, which we interpret as an intermediate energy phase, a strongly coupled liquid with nontrivial scaling behavior in the time direction. We aim to describe what kind of phases and phase transitions holographic systems exhibit from the viewpoint of this liquid phase. Various instabilities are identified. For example in one of our exotic phase transitions we find a finite susceptibility, but an infinite correlation length at the critical point. From these studies we hope to get inspiration on how to get a handle on hard problems in real condensed matter systems.

Rafael Nepomechie, (Miami)

Title: Integrability in twisted AdS/CFT

Abstract: There is overwhelming evidence that AdS5/CFT4 is integrable. We review some recent results suggesting that integrability persists in a deformation of the theory corresponding to twists in the worldsheet S-matrix and boundary conditions.

Stefano Nicotri, (Bari)

Title: Getting hints on the QCD phase diagram through bottom-up holography

Abstract: We investigate the deconfinement transition in QCD-like theories at finite temperature and chemical potential by studying the heavy quark-antiquark free energy through bottom-up holographic methods. The resulting deconfinement line in the \\mu-T plane is in agreement with phenomenology, and the critical value of the chemical potential is extracted.

Bengt. E.W. Nilsson, (Chalmers)

Title: Topologically gauged BLG/ABJM theory and chiral gravity

Abstract: We discuss recent developments in AdS/CFT concerning the possibility of introducing boundary conditions that lead to boundary theories with dynamical gravity. We then construct BLG/ABJM theories with gauged global symmetries that should arise in this generalized AdS/CFT context.

Chanyong Park, (Seoul)

Title: Correlation Functions of the Solitonic String

Abstract: We investigate the two- and three-point correlation functions of the solitonic string moving in the Poincare $AdS$ and three-dimensional sphere. After calculating the three-point correlation function between two heavy operators corresponding to the magnon or spike and one marginal scalar operator, we show that the coupling between those operators in string theory is exactly the same as one obtained by the RG analysis in the gauge theory.

Jaemo Park, (Pohang)

Title: Probing dualities by index computation

Abstract: We explore the various dualities using the index computation. We work out the index of 3-d theories related by Seiberg-like dualities and find perfect agreements. We also work out the index of 3-d mirror pairs with N=4 supersymmetry and the corresponding N=4 Chern-Simons matter theories and find prefect agreements. Finally we work out the superconformal index for candidate AdS4/CFT3 dual pairs with N=2 supersymmetry.

Alexander Patrushev, (Ontario)

Title: Exotic black holes: correlated stability conjecture, Eling-Oz formula for bulk viscosity

Abstract: We analyze black hole solutions of the model with scalar hair proposed by Buchel and Pagnutti. First, this model appears to be the counterexample for correlated stability conjecture connecting thermodynamic and classical (in)stabilities of black branes. Second, we discuss dual hydrodynamic properties and show that Elling-OZ formula for bulk viscosity is valid for all the temperatures.

Maurizio Piai, (Swansea Univ.)

Title: Walking dynamics from gauge-gravity dualities.

Abstract: Dynamical electroweak symmetry breaking will be tested at the Large Hadron Collider. Gauge-gravity dualities offer an ideal tool for the study of this scenario, in which the underlying dynamics is strongly coupled and very different from QCD. Some specific models, built within Type IIB string theory with backgrounds related to the conifold, exhibit the feature of a light scalar particle in the spectrum, which might mimic many of the signatures of the Standard Model Higgs.

Alex Pomarol, (Barcelona, UAB)

Title: AdS/CFT and compositeness in the SM

Abstract: We use the AdS/CFT correspondence to study the implications of compositeness in the particle spectrum of the SM and how this could be tested at the LHC.

Vidas Regelskis, (York)

Title: Integrable boundaries in AdS/CFT

Abstract: The recent progress in solving the planar limit of AdS/CFT was accelerated a lot by the underlying integrability. The striking success in finding the scattering S-matrices and reflection K-matrices from various boundaries was achieved due to the underlying centrally-extended su(2|2) algebra and it's Yangian extension. In this talk I shall focus on the Yangian symmetry related to the reflection from the D3 and D5 branes. The reflection depends crucially on the orientation of the brane inside the AdS_5 x S^5 space and the choice of vacuum. Some cases allow a `twisted boundary Yangian' structure which is a co-ideal subalgebra of the usual Yangian of the bulk S-matrix. In particular, I will consider the twisted Yangian of the Y=0 D3 brane and the achiral twisted Yangian of D5 brane.

Soo-Jong Rey, (Seoul Nat. Univ.)

Title: Nonlinear W(infinity) Symmetry in 3d Higher Spin AdS/CFT

Abstract: In this talk, I present new results on AdS/CFT for 3d higher spin gauge theory, which is believed to describe tensionless limit of string theory. By analyzing asymptotic symmetry in the bulk, we argue that the boundary CFT must have W(infinity) symmetry. The symmetry algebra has a classical central charge c = 6k = L/3G. I will discuss implications of this to the boundary CFT, especially, for microstates of black holes. I will also generalize it to maximally extended supersymmetric setup and emphasize some peculiarities compared to bosonic case. I will also discuss applications of this new findings to AdS/CMT and AdS/QCD.

Alberto Salvio, (Pisa)

Title: The Little-Parks Effect and Quantum Hair on (Holographic) Superconductors

Abstract: Superconductors in a large-radius cylindrical geometry threaded by a magnetic flux display the so-called Little-Parks effect - a periodicity in the flux with period hc/2e. The Aharonov-Bohm effect, instead, is hc/e-periodic and it can uplift the degeneracy of the Little-Parks sub-periods for small enough cylinder radii. In Holographic Superconductors, the Little-Parks degeneracy and its uplifting are simply understood as the response to a Quantum Hair given by a magnetic discrete gauge charge. The uplifting is suppressed in the deconfining (Black Hole) phase and unsuppressed in the confining (AdS Soliton) phase as a result of a large N (classical) no-hair theorem. It will also be discussed a Ginzburg-Landau description to the uplifting of the Little-Parks degeneracy.

Yuji Satoh, (Tsukuba)

Title: g-functions and gluon scattering amplitudes at strong coupling

Abstract: We discuss gluon scattering amplitudes of N=4 SYM at strong coupling by using the thermodynamic Bethe ansatz equations/Y-system and conformal perturbation theory. An interesting relation between Y-functions and g-functions (boundary entropy) enables us to derive analytic expansions of the amplitudes around kinematic points of equal cross-ratios of external momenta. We obtain the expansions explicitly for the amplitudes corresponding to the minimal surfaces in AdS_3, and find that appropriately rescaled remainder functions are very similar to those at weak coupling.

Andreas Schmitt, (Vienna)

Title: Inverse magnetic catalysis in dense holographic matter

Abstract: We study the chiral phase transition in a magnetic field at finite temperature and chemical potential within the Sakai-Sugimoto model, a holographic top-down approach to (large-N_c) QCD. We consider the limit of a small separation of the flavor D8-branes, which corresponds to a dual field theory comparable to a Nambu-Jona Lasinio (NJL) model. Mapping out the surface of the chiral phase transition in the parameter space of magnetic field strength, quark chemical potential, and temperature, we find that for small temperatures the addition of a magnetic field decreases the critical chemical potential for chiral symmetry restoration - in contrast to the case of vanishing chemical potential where, in accordance with the familiar phenomenon of magnetic catalysis, the magnetic field favors the chirally broken phase. This ``inverse magnetic catalysis\'\' (IMC) appears to be associated with a previously found magnetic phase transition within the chirally symmetric phase that shows an intriguing similarity to a transition into the lowest Landau level. We estimate IMC to persist up to $10^{19}\\, {\\rm G}$ at low temperatures.

Yunseok Seo, (Seoul)

Title: Baryons and mesons in dense system

Abstract: The behavior of hadrons at finte density is very hard to understand even in lattice QCD. To study density or chemical potential dependence of hadrons, we construct a simple D-brane model. From this model, we investigate several properties of hadrons in dense system.

Shigeki Sugimoto, (Tokyo, IPMU)

Title: Holographic Description of Hadrons from String Theory

Abstract: I will give an overview of holographic QCD, which is an attempt to apply the idea of gauge/string duality to QCD and hadron physics. In particular, I will discuss that various mesons found in the experiment are described as open string states.

Ryo Suzuki, (Utrecht)

Title: Hybrid nonlinear integral equations for AdS_5 x S^5

Abstract: The exact quantum spectrum of string states on AdS_5 x S^5 is expected to be given by Thermodynamic Bethe Ansatz (TBA) equation. However, it is not easy to analyze TBA because it involves infinitely many Y-functions. In this talk, I will explain how to simplify TBA for superstring on AdS_5 x S^5 via the decomposition of Y-functions into constituents; like mesons into quarks. This method is based on A1 symmetry, integrability and analyticity, and thus applicable to other integrable models.