I will discuss work in progress on defining hydrodynamics for fluids without boost symmetries. We treat velocity as a chemical potential whose conjugate variable is momentum. This leads to a formalism that unifies relativistic, non-relativistic and ultra-relativistic hydrodynamics into one framework where the different cases are distinguished by a simple choice of equation of state for the momentum of the fluid. By taking other equations of state for the momentum we can also treat fluids without boost symmetries. These may be relevant for certain condensed matter systems.

The talk is based on a work in progress with Valentin Reys on generalized Rademacher sum.
I will first review the construction of (mock) modular forms via Rademacher sum and then derive a generalization of this technique in the case of mixed mock modular forms. These include counting functions of single centered BH's in N=4 supergravity in 4D. The result obtained will be eventually compared with the computation of the quantum entropy function (arxiv:1512.01553).

Abstract: I will explain Verlinde’s formula for apparent dark matter and give a heuristic derivation. Moreover I will discuss some recent observations in galaxies, both from rotation curves (McGaugh et al.) and from weak gravitational lensing (Brouwer), that strongly support Verlinde’s theory.

Papers:
Verlinde, “Emergent Gravity and the Dark Universe,” to appear soon
Brouwer, KiDS collaboration, MV, “First observational test of Verlinde’s theory of Emergent Gravity using Weak Gravitational Lensing,” to appear soon
McGaugh, Lelli, Schombert, “The Radial Acceleration Relation in Rotationally Supported Galaxies,” arXiv:1609.05917

Title: Universal Properties After a Quantum Quench in CFT

Abstract: I will present the problem of a quantum quench in QFT, i.e., following the real-time evolution of an operator whose coupling is rapidly changing in time. Inspired by results in holography, we find certain universal scaling properties for fast and smooth quenches. We provide evidence for it in free field theories and provide a general argument for arbitrary CFTs. If time allows, I will discuss different interesting properties such as their relation to the sudden quench, quenches through critical points, quenches in exactly solvable lattice models, etc…

References: 1401.0560, 1411.7710, 1505.05224, 1602.08547 and some unpublished work in progress.

Dec 16:Jelle Hartongwill tell us about:

Fluids without boost symmetry

Abstract:

I will discuss work in progress on defining hydrodynamics for fluids without boost symmetries. We treat velocity as a chemical potential whose conjugate variable is momentum. This leads to a formalism that unifies relativistic, non-relativistic and ultra-relativistic hydrodynamics into one framework where the different cases are distinguished by a simple choice of equation of state for the momentum of the fluid. By taking other equations of state for the momentum we can also treat fluids without boost symmetries. These may be relevant for certain condensed matter systems.

And we will informally discuss:

1. Sub-AdS Scale in AdS_3/CFT_2 (JFK+B)

2. Entanglement equilibrium for higher order gravity (Bueno, Min, Speranza, MV)

3. Fast and Slow Coherent Cascades in Anti-de Sitter Spacetime (Fotis, Juan and Ben)

4. K3 String Theory, Lattices and Moonshine (Miranda et al)

5. Loops in AdS from Conformal Field Theory (Aharony et al)

Dec 9:Francesca FerrariA Mixed Farey TailThe talk is based on a work in progress with Valentin Reys on generalized Rademacher sum.

I will first review the construction of (mock) modular forms via Rademacher sum and then derive a generalization of this technique in the case of mixed mock modular forms. These include counting functions of single centered BH's in N=4 supergravity in 4D. The result obtained will be eventually compared with the computation of the quantum entropy function (arxiv:1512.01553).

And we will informally discuss:

1. Topological classification of crystalline insulators through band structure combinatorics(Kruthoff, de Boer, van Wezel, Kane, Slager)

2. More N=4 superconformal bootstrap(Beem, Rastelli,van Rees)

3. Thermoelectric transport in disordered metals without quasiparticles: the SYK models and holography (Davison et. al)

4. The Spectrum of Static Subtracted Geometries (Tomas Andrade, Alejandra Castro, Diego Cohen-Maldonado)

5. Sub-AdS Scale in AdS_3/CFT_2 (JFK+B)

Nov 24:Informal Paper discussion@12.00

We will informally discuss:

1. 2D CFT Partition Functions at Late Times (Dyer, Gur-Ari)

2. Black Holes and Random Matrices (Shenker, Polchinski et al)

3. Four-dimensional black holes in Einsteinian cubic gravity (Bueno, Cano)

4. Electromagnetic duality and entanglement anomalies (Donnelly, Michel, Wall)

Nov 11: Faculty member corner - Diego HofmanAnd we will informally discuss:

1. Aspects of higher-order gravities (Bueno, Cano, Min, Visser)

2. Bulk Fields from the boundary OPE (Guica)

3. Emergent Gravity and the Dark Universe (Verlinde)

4. Relative entropy of excited states in conformal field theories of arbitrary dimensions (Sarosi, Ugajin)

Nov 4: Manus VisserTitle: Emergent Gravity and the Dark Universe

Abstract: I will explain Verlinde’s formula for apparent dark matter and give a heuristic derivation. Moreover I will discuss some recent observations in galaxies, both from rotation curves (McGaugh et al.) and from weak gravitational lensing (Brouwer), that strongly support Verlinde’s theory.

Papers:

Verlinde, “Emergent Gravity and the Dark Universe,” to appear soon

Brouwer, KiDS collaboration, MV, “First observational test of Verlinde’s theory of Emergent Gravity using Weak Gravitational Lensing,” to appear soon

McGaugh, Lelli, Schombert, “The Radial Acceleration Relation in Rotationally Supported Galaxies,” arXiv:1609.05917

And we will informally discuss:

1. Resurgence matches quantization (R. Couso-Santamaría, M. Mariño and R. Schiappa)

2. Replica trick and string winding (Prudenziati, Trancanelli)

3. Einstein gravity 3-point functions from conformal field theory (Afkhami-Jeddi, Hartman, Kundu and Tajdini).

4. Relative entropy and the RG flow (Casini, Teste, Torroba)

5. An SYK-Like Model Without Disorder (Witten)

6. Aspects of higher-order gravities (Bueno, Cano, Min, Visser)

7. Four-dimensional black holes in Einsteinian cubic gravity (Bueno, Cano)

8. Bulk Fields from the boundary OPE (Guica)

Oct 21:Damian Galante:Title: Universal Properties After a Quantum Quench in CFT

Abstract: I will present the problem of a quantum quench in QFT, i.e., following the real-time evolution of an operator whose coupling is rapidly changing in time. Inspired by results in holography, we find certain universal scaling properties for fast and smooth quenches. We provide evidence for it in free field theories and provide a general argument for arbitrary CFTs. If time allows, I will discuss different interesting properties such as their relation to the sudden quench, quenches through critical points, quenches in exactly solvable lattice models, etc…

References: 1401.0560, 1411.7710, 1505.05224, 1602.08547 and some unpublished work in progress.

And we will informally discuss:

1. Compensating strong coupling with large charge (Alvarez-Gaume et. al)

2. Vacua Morghulis (Freivogel, Kleban)3. Bootstrapping Pure Quantum Gravity in AdS3 ( J-B Bae, K. Lee and S. Lee)

4. Universality of sparse d > 2 conformal field theory at large N ( A. Belin, J. de Boer, J. Kruthoff, et. al)

5. The fate of chaotic strings in a confining geometry (Ishii, Takaaki; Murata, Keiju; Yoshida, Kentaroh)

Oct 14:Marcos Crichigno, Universal RG flows across dimensionsAnd we will informally discuss:

1. Eigenstate Thermalization Hypothesis in Conformal Field Theory (Lashkari, Dymarsky, Liu)

2. The NUTs and bolts of squashed holography (Bobev, Hertog, Vreys)

3. Equivalence of two contour prescriptions in superstring perturbation theory (Sen)

4. Noether charge, black hole volume and complexity (Couch, Fischler, Nguyen)

5. Hamiltonian Analysis of an On-shell U(1) Gauge Field Theory (Lin, Sasaki)

Oct 7:Speaker DiscussionAnd we will informally discuss:

1. Bulk Locality and Entanglement Swapping in AdS/CFT (Kelly)

2. Localization of supersymmetric field theories on non-compact hyperbolic three-manifolds (Assel, Martelli, Murthy, Yokoyama)

3. Non-supersymmetric AdS and the swampland (Ooguri, Vafa)

4. A generalization of Sachdev-Ye-Kitaev (Gross, Rosenhaus)

5. The NUTs and bolts of squashed holography (Bobev, Hertog, Vreys)

6. Superrotations and black hole pair creation (Strominger, Zhiboedov)

7. Equivalence of two contour prescriptions in superstring perturbation theory (Sen)

8. Eigenstate Thermalization Hypothesis in Conformal Field Theory (Lashkari, Dymarsky, Liu)

Sep 23:Bert Vercnocke will tell us about:" Quantum gravity features in black hole observations?! "

And we will informally discuss:

1. From path integrals to tensor networks for AdS/CFT (Miyaji, Takayanagi, Watanabe)

2. Unstoppable brane-flux decay of anti-D6 branes (U.H. Danielsson, F. F. Gautason, T. Van Riet)

3. A conformal block Farey tail (A. Maloney, H. Maxfield, G. S. Ng)

Sep 16:Sagar Lokhande will tell us about:"

Quantum Quenches: CFT and a bit of Holography"He will try to summarize the ideas/methods/results from (some of) the following references:

1. Calabrese and Cardy - Quantum quenches in 1+1 dimensional CFTs

2. Balasubramanian et.al. - Holographic thermalization

3. Buchel et.al. - Universality of abrupt holographic quenches

4. Das - Holographic quantum quench

And we will informally discuss:

1. On Volumes of Subregions in Holography and Complexity (Ben-Ami, Carmi)

2. Soft Black Hole Absorption Rates as Conservation Laws (S. Avery, B. Schwab)

Sep 9:Benjamin Mosk will tell us about:"Equivalent Equations of Motion for Gravity and Entropy" (Canceled)

And we will informally discuss:

1. A CFT perspective on gravitational dressing and bulk locality (Lewkowycz, Turiaci, Verlinde)

2. The complexity of identifying Ryu-Takayanagi surfaces in AdS3/CFT2 (Bao and Chatwin-Davies)

3. A Cardy Formula for Three-Point Coefficients: How the Black Hole Got its Spots (Kraus and Maloney)

4. Entanglement Growth after a Global Quench in Free Scalar Field Theory ( Cotler, Hertzberg, Mezei and Mueller)

Sep 2:Laurens Kabir will tell us about:"Bulk Locality in AdS/CFT".We will informally discuss:

1. The Goldstino Brane, the Constrained Superfields and Matter in N=1 Supergravity (Bandos, Heller, Kuzenko, Martucci and Sorokin)

2. Traversable Wormholes via a Double Trace Deformation (Gao, Jafferis, Wall)

3. On the gauge dependence of the AdS instability problem (Dimitrakopoulos, Freivogel, Pedrazza, Yang)

4. A CFT perspective on gravitational dressing and bulk locality (Lewkowycz, Turiaci, Verlinde)