Black Holes and Emergent Spacetime

8 Aug 2016, 09:00 → 2 Sept 2016, 18:00 Europe/Stockholm

122:026 (Nordita, Stockholm)

Bo Sundborg, Lárus Thorlacius, Monica Guica, Niels Obers

Venue

Nordita, Stockholm, Sweden

Scope

This Nordita Program will develop two interrelated themes to provide new insights into the underlying holographic structure of space-time and the quantum nature of black holes. We will focus on the interplay between quantum entanglement, entropy and the emergence of space-time from quantum field theory in the context of holographic dualities. A parallel theme involves extending the notion of holographic duality to more general classes of space-times. Widening the scope of the holographic paradigm will open up new avenues for applied holography and may shed light on some deep puzzles in quantum cosmology. The program aims at bringing together experts in this exciting research field and introduce PhD students and younger researchers to these developments.

[Timetable - available from start of the program]

Format

There will be typically one or two talks per day, leaving ample time for interaction and collaboration. At the start of each week a pedagogical introductory lecture is planned on one of the central topics. A conference with a full schedule of talks will take place on August 17-20.

Application

If you want to apply for participation in the program, please fill in the application form. You will be informed by the organizers shortly after the application deadline whether your application has been approved. Due to space restrictions, the total number of participants is strictly limited.

Application deadline: March 31, 2016

A minimum stay of one working week is required and participants are encouraged to stay for a period of at least two weeks. The minimum stay rule does not apply if you are only attending the conference on August 17-20, but in that case you should not register here but rather on the conference homepage.

Please note that registered program participants, whose stay includes August 17-20, do not need to separately register for the conference.

There is no registration fee.

Travel Reimbursement

PhD students and Postdoctoral fellows are eligible for travel grants to participate in the program. If you are interested in such a grant, please mark the corresponding field in the application form, briefly summarize your research interests in the place provided, and indicate in the comments field an estimate of your expected travel expenses. Since only a limited number of travel grants is available, decision concerning the grants will be made on a case-by-case basis and you will be notified shortly after the application deadline.

Accommodation

Nordita provides a limited number of rooms in the Stockholm apartment hotel BizApartments free of charge for accepted participants.

Sponsored by:

Monday, 8 August

1 Bulk solutions for non-trivial boundary topology

I will discuss two recent explorations of the AdS_3/CFT_2 correspondence for non-trivial boundary topology: calculating the action for bulk handlebodies for Riemann surfaces, and obtaining the bulk saddles and their action for non-orientable boundaries.

Speaker: Prof. Simon Ross (Durham University)

Tuesday, 9 August

2 Boundary effects in entanglement entropy

Speaker: Prof. Sergey Solodukhin (University of Tours)

3 Area, entanglement entropy and supertranslations at null infinty

Speaker: Prof. Andrew Strominger (Harvard University)

Wednesday, 10 August

4 Infalling observers and small black holes

I discuss a sense in which bulk fields can be partially reconstructed in the interior of an AdS black hole in terms of data in the CFT. This reconstruction enables a classical description of infalling observers, even at late times in a small evaporating black hole. But at late times it does not allow for a complete reconstruction of the interior geometry, which may have implications for information recovery.

Speaker: Prof. Dan Kabat (City University of NY)

5 Smooth causal patches for AdS black holes

We describe an apparent paradox with state-dependent constructions of the black hole interior: excitations with small energy with respect to the boundary Hamiltonian can have strong effects on an infalling observer violating a principle of statistical mechanics that bounds the effect of low-energy sources. This is sometimes called a "Born rule" violation. We describe how this paradox is resolved by causality. As a result of a non-trivial property of position-space AdS correlators, no observer can create such an excitation and also observe its effect. This is an important check of the consistency of state-dependent maps between the black hole interior and boundary operators in AdS/CFT.

Speaker: Prof. Suvrat Raju (Centre for Theoretical Sciences, Tata Institute of Fundamental Research)

Thursday, 11 August

6 Newton-Cartan and Carrollian geometry in holography and hydrodynamics

I will give an introduction and overview of Newton-Cartan and Carrollian geometries. These geometries appear as boundary geometries in non-AdS holography, in novel types of gravitational theories such as Horava-Lifshitz gravity and in applications to low energy physics such as e.g. non-relativistic hydrodynamics. In the first part I will introduce the basic ingredients of Newton-Cartan and Carrollian geometries and discuss their appearance in holography. In the second part I will focus on applications to hydrodynamics for systems with dynamical exponent z>1.

Speaker: Dr Jelle Hartong (ULB)

7 Kerr-Newman black holes in supergravity

Speaker: Prof. Finn Larsen (University of Michigan)

Friday, 12 August

8 Interacting giant gravitons from Spin Matrix Theory

Using the non-abelian DBI action we find an effective matrix model that describes the dynamics of weakly interacting giant gravitons wrapped on three-spheres in the AdS part of AdS_5 x S^5 at high energies with two angular momenta on the S^5. In parallel we consider the limit of \CN=4 super Yang-Mills theory near a certain unitarity bound where it reduces to the quantum mechanical theory called SU(2) Spin Matrix Theory. We show that the exact same matrix model that describes the giant gravitons on the string theory side also provides the effective description in the strong coupling and large energy limit of the Spin Matrix Theory. Thus, we are able to match non-supersymmetric dynamics of D-branes on AdS_5 x S^5 to a finite-N regime in \CN=4 super Yang-Mills theory near a unitarity bound.

Speaker: Prof. Troels Harmark (Niels Bohr Institute)

9 Coarse grained dynamics and holography

Speaker: Prof. Albion Lawrence (Brandeis University)

Monday, 15 August

10 AdS2 holography and non extremal black holes

Speaker: Dr Ioannis Papadimitriou (SISSA)

11 Entwinement in discretely gauged theories

The concept of "entwinement" originated in the ongoing program of reconstructing spacetime from quantum entanglement in holographic duality. We develop this notion, which characterizes the amount of entanglement between internal, discretely gauged degrees of freedom, from a quantum field theory point of view.

Speaker: Prof. Ben Craps (VUB)

Tuesday, 16 August

12 Microstate geometries and gravitational collapse

I will first review recent progress on 'microstate geometries', horizon-less solutions of string theory that play a role in the fuzzball proposal. Then I will discuss how gravitational collapse might end in a microstate geometry rather than in a black hole end state, through quantum tunneling.

Speaker: Dr Bert Vercnocke (University of Amsterdam)

13 New exact entanglement entropies

Speaker: Prof. Stefan Vandoren (University of Utrecht)

Monday, 22 August

14 From Planck data to Planck era: Observational tests of Holographic Cosmology

I will present holographic models for the very early Universe, the period usually associated with inflation, and compare the predictions of these models against Planck 2015 data. Within the holographic framework the early Universe is described by a three dimensional QFT. Conventional inflation is included in this framework as strong coupled QFT while qualitatively new models arise when the QFT has weak or intermediate coupling. The weakly coupled models describe a very quantum early Universe and it turns out that these models fit the Planck data remarkably well, providing an alternative to LambdaCDM. Observations can be used to exclude some QFT models, while we also find models satisfying all phenomenological constraints: the data rules out the dual theory being Yang-Mills theory coupled to fermions only, but allows for Yang-Mills theory coupled to non-minimal scalars with quartic interactions.

Speaker: Prof. Kostas Skenderis (University of Southampton)

15 (Nordita seminar) Relativistic hydrodynamics as an effective field theory

Hydrodynamics is a rather old subject, but in the last few years we have seen enormous progress in understanding some of the theoretical underpinnings of the subject. I will explain how the standard axioms of the phenomenological theory can be explicitly solved for allowed forms of transport. The solution reveals some interesting hidden symmetries which we will explain from a microscopic perspective. We shall see that the effective field theory of non-linear dissipative fluids is described in terms of a novel topological sigma model.

Speaker: Prof. Mukund Rangamani

16 Welcome reception

Tuesday, 23 August

17 Worldline Holography and the Static Patch

Speaker: Dr Dionysios Anninos (IAS)

18 Emergence and Violation of Locality in Quantum Gravity

I will discuss progress and puzzles in understanding the emergence of bulk locality in the context of simple models of the AdS/CFT correspondence.

Speaker: Prof. Ben Freivogel (University of Amsterdam)

Wednesday, 24 August

19 Gauge theory description of black hole evaporation

We show how hot, evaporating black holes are described by gauge theories. This talk consists of four parts, which are related but can be understood to some extent independently: (1) Precision test of the gauge/gravity duality at finite temperature by lattice simulations (Reference [1,2]), (2) The microscopic description of the evaporation of black holes based on gauge theories (Reference [3,4]), (3) The microscopic description of the 10d Schwarzschild black hole by 4d N=4 SYM (Reference [5]), (4) The emergence of the black hole horizon from gauge theory (Reference [6]). In part (1), I explain the state-of-the-art numerical studies of super Yang-Mills theories, in particular the supercomputer simulations of D0-brane quantum mechanics. This year, the large-N and continuum limits are taken for the first time, and the gauge/gravity duality conjecture at finite temperature has been tested very precisely. Both the leading supergravity part and stringy corrections has been reproduced rather precisely. In part (2), we attack one of the biggest mystery of the gauge/gravity duality -- can gauge theories describe evaporating black holes with the negative specific heat? We point out that the previous analyses missed the process of the emission of D-branes (eigenvalues of matrices), and with a proper treatment of this process, the evaporation and negative specific heat are inevitable consequences in rather generic class of black holes with gauge theory duals. For the case of black zero-brane, we analyze the evaporation process quantitatively by using analytic methods. In part (3), we apply the same idea to 4d N=4 SYM on three-sphere. Then the microscopic description of the small 10d black hole and the Hagedorn behavior can be obtained rather straightforwardly. In part (4), we consider the 'bulk geometry' by looking at gauge theory. More specifically, we study the force acting on D-branes in gauge theory side. We argue that the horizon is only an approximate concept at large-N; it becomes obscure, or 'disappear', at finite-N. We see how this picture is related to the evaporation described in part (3). References: [1] E. Berkowitz, E. Rinaldi, M. Hanada, G. Ishiki, S. Shimasaki and P. Vranas (Monte Carlo String/M-theory Collaboration), ``Supergravity from D0-brane Quantum Mechanics,'' arXiv:1606.04948 [hep-th]. [2] E. Berkowitz, E. Rinaldi, M. Hanada, G. Ishiki, S. Shimasaki and P. Vranas (Monte Carlo String/M-theory Collaboration), ``Precision lattice test of the gauge/gravity duality at large-N,'' arXiv:1606.04951 [hep-lat]. [3] E. Berkowitz, M. Hanada and J. Maltz, ``Chaos in Matrix Models and Black Hole Evaporation,'' arXiv:1602.01473 [hep- th]. [4] E. Berkowitz, M. Hanada and J. Maltz, ``A microscopic description of black hole evaporation via holography,'' arXiv:1603.03055 [hep-th]. [5] M. Hanada, J. Maltz and L. Susskind, in preparation. [6] E. Berkowitz, G. Gur-Ari, M. Hanada, J. Maltz, E. Rinaldi and P. Vranas, in preparation.

Speaker: Prof. Masanori Hanada (Kyoto University & Stanford University)

20 Poking Holes in Hole-ography

Hole-ography (or alternatively, differential entropy) is a promising tool for reconstructing a three-dimensional holographic bulk from the structure of the entanglement entropy of its CFT dual. However, there are generically regions in the interior of event horizons where the hole- ographic reconstruction must fail, even if one admits so- called "long" geodesics (conjectured to correspond to "entwinement" in the CFT). These regions correspond to the interiors of so-called holographic screens, which are a local generalization of event horizons and which can be interpreted holographically via the Bousso bound. In this talk, I will review the hole-ographic approach and holographic screens, and then prove that hole-ography must fail inside of these screens.

Speaker: Dr Sebastian Fischetti (Imperial College London)

Thursday, 25 August

21 Constraints on CFT three point functions

We discuss methods to analytically obtain constraints on the OPE coefficients of an arbitrary CFT (in d>3 dimensions). One of them is the positivity of the energy flux; another one involves deep inelastic scattering thought experiments. We derive bounds on the OPE coefficients of various operators using both methods. We discuss under which conditions the constraints derived are equivalent.

Speaker: Prof. Manuela Kulaxizi (Trinity College Dublin)

22 Canonical Heterotic Throats

Note: precise starting time might change

Speaker: Prof. Nick Halmagyi (LPTHE)

23 Weyl anomalies and quantum cosmology

Speaker: Prof. Atish Dabholkar (ICTP)

Friday, 26 August

24 Aspects of higher spin black holes

We discuss various aspects of three-dimensional higher spin black holes, in the context of the AdS_3/CFT_2 correspondence. In particular, we describe how to exploit the Chern-Simons formulation of higher spin theories in AdS_3 in order to derive properties of 2d CFTs with extended symmetry algebras, in the semiclassical (large central charge) limit. We will mainly focus on 2d CFTs with W- symmetry, and comment on how to derive their thermodynamic and modular transformation properties, entanglement entropy, supersymmetry and BPS bounds, by studying black hole solutions in the dual Chern-Simons theories.

Speaker: Dr Juan Jottar (ETH Zurich)

25 Generalized global symmetries, dissipative magnetohydrodynamics, and holography

Just as ordinary global symmetries in quantum field theory are associated with conserved currents that count particle numbers, “generalized” global symmetries are associated with higher-form conserved currents that can be understood as counting higher-dimensional objects such as strings. I will discuss how this idea applies to the long-distance structure of theories of electromagnetism, where a key role is played by a higher-form conserved current that counts the density of magnetic flux lines. I will then use this higher form current to reformulate dissipative magnetohydrodynamics from the point of view of generalized symmetries and effective field theory. I will also discuss the structure of the holographic dual to magnetohydrodynamics, which involves a two-form field propagating in the bulk.

Speaker: Prof. Nabil Iqbal (University of Amsterdam)

Monday, 29 August

26 Some geometrical aspects of entanglement in CFT & Holography

In the first part we discuss the holographic entanglement entropy in AdS4/CFT3 for finite domains with generic shapes. For smooth shapes the constant term can be evaluated by employing a generalisation of the Willmore functional for two dimensional surfaces. Explicit examples are given for asymptotically AdS4 black holes, domain wall geometries and time dependent backgrounds. The second part is focused on the entanglement negativity in CFT. In 2+1 dimensions we present some numerical results for two adjacent regions in a two dimensional harmonic lattice, discussing the area law behaviour and the corner contributions. In 1+1 dimensions and for two disjoint intervals in the Ising and the Dirac fermion models, we show that the contribution of a given spin structure to the moments of the partial transpose is obtained as the scaling limit of a specific lattice term. This analysis provides also the moments of the partial transpose for the free fermion.

Speaker: Prof. Erik Tonni (SISSA)

Tuesday, 30 August

27 Entanglement, holography and causal diamonds

The talk will discuss novel geometric structures introduced in 1606.03307‎ and will focus on their applications to the entanglement entropy in CFTs and the Ryu-Takayanagi prescription.

Speaker: Dr Michal Heller (Perimeter Institute for Theoretical Physics)

text heller-2016.pdf

Wednesday, 31 August

28 Entanglement propagation in 2d CFTs

I will discuss the time evolution of entanglement measures and out-of-time order correlators in excited states of 2d CFTs. In particular, I will stress the differences between holographic and non-holographic models from the perspective of the entanglement dynamics and scrambling.

Speaker: Dr Pawel Caputa (Nordita)