UvA Strings Journal Club Wiki

Here we will keep a list of papers for discussion at the journal club. If you see a paper that seems interesting during the week (up to Wed), just add it to the list and the organizer (i.e. Damian) will bring it up during the journal club on Friday. The Edit button is in the drop-down menu that appears if you click the arrow on the top right.


Feb 21: Sagar Lokhande

Title: TBA
Abstract: TBA


March 2: Hongliang Jiang

and we will discuss:

Journal Clubs of the Recent Past

Feb 16: Fernando Rejon-Barrera

Title: Weight Shifting Operators and Conformal Blocks
by Denis Karateev, Petr Kravchuk, David Simmons-Duffin
We introduce a large class of conformally-covariant differential
operators and a crossing equation that they obey. Together, these
tools dramatically simplify calculations involving operators with spin
in conformal field theories. As an application, we derive a formula
for a general conformal block (with arbitrary internal and external
representations) in terms of derivatives of blocks for external
scalars. In particular, our formula gives new expressions for "seed
conformal blocks" in 3d and 4d CFTs. We also find simple derivations
of identities between external-scalar blocks with different dimensions
and internal spins. We comment on additional applications, including
derivation of recursion relations for general conformal blocks,
reducing inversion formulae for spinning operators to inversion
formulae for scalars, and deriving identities between general 6j
symbols (Racah-Wigner coefficients/"crossing kernels") of the
conformal group.

and we will discuss:
1- To gauge or not to gauge? (Maldacena, Milekhin)
2- Gauged And Ungauged: A Nonperturbative Test(Hanada et al)
3- Black Holes and Complexity Classes (Susskind)

Feb 9: Victor Godet

Title: Black hole entropy in ABJM theory
Abstract: I will review the microscopic derivation of the Bekenstein-Hawking entropy of AdS4 black holes from supersymmetric localization in ABJM theory (1511.04085).

and we will discuss:
1- Dirichlet-Branes and Ramond-Ramond Charges, Joseph Polchinski.
2- Renormalization and Effective Lagrangians (Joe Polchinski)
3- Why do things fall? (Susskind)

Feb 2: Eva Llabrés

Title: Wilson Lines and Ishibashi states in AdS3/CFT2

Abstract: I will present unpublished work with Alejandra Castro and Nabil Iqbal, in which we provide a refined interpretation of a gravitational Wilson line in AdS3 in terms of Ishibashi states in the dual CFT2. Our strategy is to give a method to evaluate the Wilson line that accounts for all the information contained in the representation, and clarify the role of boundary conditions at the endpoints of the line operator. This gives a novel way to explore and reconstruct the local bulk dynamics which we discuss.

and we will discuss:
1- Proof of the Weak Gravity Conjecture from Black Hole Entropy (Cheung, Liu and Remmen)
2 - Comments on a state-operator correspondence for the torus (Alex, Jan, Jorrit)

January 27: Grant Salton (Stanford)

Title: Entanglement wedge reconstruction via approximate operator algebra quantum error correction

Abstract: Quantum error correction -- originally invented for quantum computing -- has proven itself useful in a variety of non-computational physical systems, as the ideas of QEC are broadly applicable. In this talk, I'll focus on the recent discovery that even the AdS/CFT correspondence implements quantum error correction. We will study the hypothesis that any local bulk operator in AdS can be reconstructed using only a causally disconnected subregion of the CFT (the so-called entanglement wedge reconstruction hypothesis). This hypothesis has been proven correct under the assumption that error correction in AdS/CFT is exact, but this assumption is not expected to hold. Fortunately, recent advances in the theory of approximate quantum error correction have emerged, which can be leveraged to solve this problem. In this talk, we will first review these results on recoverability and approximate quantum error correction, and then we'll learn new generalizations of those ideas to both the case of recovery of quantum subsystems, as well as recovery for algebras of observables. We will then review some basics of AdS/CFT and the entanglement wedge hypothesis. With all these tools in hand, we will prove that entanglement wedge reconstruction can be done robustly, and we'll find an explicit formula for reconstructed bulk operators. Joint work with Jordan Cotler, Patrick Hayden, Brian Swingle, and Michael Walter: https://arxiv.org/abs/1704.05839

and we will discuss:
1- Extremal Tunneling and Anti-de Sitter Instantons (Lars and Jan Pieter)
2- A Local First Law of Gravity (Parikh, Sarkar, Svesko)

January 12: Sam van Leuven

Title: Towards non-AdS Holography via the Long String Phenomenon

In this talk I will present my recent paper with Erik en Manus (https://arxiv.org/abs/1801.02589), whose abstract reads:
The microscopic description of AdS space obeys the holographic principle in the sense that the number of microscopic degrees of freedom is given by the area of the holographic boundary. We assume the same applies to the microscopic holographic theories for non-AdS spacetimes, specifically for Minkowski, de Sitter, and AdS below its curvature radius. By taking general lessons from AdS/CFT we derive the cut-off energy of the holographic theories for these non-AdS geometries. Contrary to AdS/CFT, the excitation energy decreases towards the IR in the bulk, which is related to the negative specific heat of black holes. We construct a conformal mapping between the non-AdS geometries and AdS(3)xS(q) spacetimes, and relate the microscopic properties of the holographic theories for non-AdS spaces to those of symmetric product CFTs. We find that the mechanism responsible for the inversion of the energy-distance relation corresponds to the long string phenomenon. This same mechanism naturally explains the negative specific heat for non-AdS black holes and the smallness of the vacuum energy in (A)dS spacetimes.

and we will be discussing:

1. Logarithmic Corrections to Black Hole Entropy: the Non-BPS Branch (Alejandra, Victor, et al.)
2. Holographic Complexity is non-local (Fu, Maloney, Marolf,et. al.)
3. Double-trace Deformations of Conformal Correlators (Giombi, Kirilin, Perlmutter)
4. Cutoff AdS3 versus the TTbar-deformation (Kraus, Liu and Marolf)

Journal Club Etiquette:

We will have many improvements. The most important ones:

A talk is 40 minutes. To allow for questions (during and after the talk), you will be STRICTLY cut off after 45 minutes.
the topics should preferably be either own work or a current research theme, rather than one particular paper. Ideas for 'hot topics' for future JC's can be posted here
- we will stimulate working groups, new collaborations and feedback for speakers
- the moderator will keep a close watch on context and priority of papers on the list
- post papers that appeared the week ending on Wednesday, to allow more reading time.

For more improvements, see the JC Manifesto

Journal Clubs of the Distant Past:

Fall 2017
Spring 2017
Fall 2016
Spring 2016
Fall 2015
Spring 201