Holography Seminar
Time and place: Tue 2-4 pm, Seminar Room 501, DWB (additional seminars and non-standard time are listed in bold)
Trinity Term 2015 Talks:
- 26/04/2016: Alexander Zhiboedov (Harvard U.): The S-matrix Bootstrap and The Leading Regge Trajectory
Abstract: We consider a tree-level meromorphic, unitary and crossing symmetric scattering amplitude. We set up bootstrap equations and use them together with unitarity to constrain the asymptotic form of the leading Regge trajectory.
- 03/05/2016: Javier Tarrio (UL Brussels): Cold holographic matter and a color group-breaking instability
Abstract:I will describe holographic models, obtained from string theory, of strongly coupled super Yang-Mills theories at zero temperature with a finite density of matter. This region of the phase diagram of YM theories is little understood due to the lack of reliable QFT computations. In the gravity side the technical challenge lies in the backreaction of the matter sector. In the IR the system is described by a non-relativistic Lifshitz metric with running scalars and vectors, describing a thermodynamically stable phase that however suffers from a dynamical instability towards the breaking of the gauge group, which would lead to color superconductivity.
- 10/05/2016: No Seminar
- 17/05/2016: Anton Rebhan (TU Wien): Semi-holography for heavy-ion collisions
Abstract: In JHEP 06 (2015) 003, Iancu and Mukhopadhyay have proposed a semi-holographic model for heavy-ion collisions, where the classical Yang-Mills equations used to describe pre-equilibrium "glasma" evolution in heavy-ion collisions are coupled to a more strongly interacting infrared section described by a holographic dual of a conformal field theory. The long-term goal is to study thermalization in a situation where part of the modes is described by perturbative QCD and part by gauge/gravity duality. I shall describe the progress made recently [arXiv:1512.06445 in collaboration with F. Preis, A. Mukhopadhyay, and S. Stricker], which involves a slight but important modification that in particular allows for the definition of a local conserved energy-momentum tensor for the combined system, and which is then tested in a simple situation with a gravity dual that is under full analytical control.
- 24/05/2016: No seminar
- 31/05/2016: Massimo Porrati (New York University): On a Canonical Quantization of Pure AdS3 Gravity
Material:Abstract: I review results and open issues of the canonical "constrain-first" approach to pure gravity in AdS3. In particular, I examine the connection with quantization of Teichmuller space, Liouville CFT, and the role of large diffeomorphisms. The main result is a well defined proposal for the scalar product of the Hilbert space of pure gravity. By requiring normalizability of the wave function we find novel constraints on the would-be holographic dual of pure gravity. I will discuss features, consequences and problems of the approach and show how the case of highly curved AdS3 may solve some of its problems.
- 06/06/2016 (Monday), 4:30 pm - 6:30 pm, room 501 DWB: Toby Wiseman (Imperial College, London): Energy bounds in holographic CFTs
Abstract: While the vacuum state of a relativistic QFT may be relatively simple in flat spacetime, for a QFT in a static but curved spacetime, or deformed by spatially depended sources for local operators, already the vacuum and its properties are subtle. A basic example is the Casimir effect which arises from the vacuum energy for QFTs in curved or non-trivial spacetimes. I will discuss how we may gain physical information about holographic CFTs placed on static but generally curved spacetimes (sometimes also allowing spatially dependent sources for certain bulk fields) using the existence of a gravity dual solving the Einstein equations. For example, using simple geometric methods we can obtain bounds on the local energy density, both showing the energy must be negative in certain regions of the space the CFT is defined on, and positive elsewhere.
- 07/06/2016: Ehsan Hatefi (Institute for Theoretical Physics, TU Wien): Black hole formation and Critical Collapse in the Axion-Dilaton System in Diverse Dimensions
Abstract: In the first part of my talk we try to come up with some basic notions about the subject and Black hole formation, explaining some details of the whole subject on GR and also why we have three different assumptions or ans\"atze for axion-dilaton system. Then we try to study the gravitational collapse of the axion-dilaton system suggested by type IIB string theory in dimensions ranging from four to ten. We would like to extend the previous analysis in the literature concerning the role played by the global SL(2, R) symmetry, evaluating the Choptuik exponents for different elliptic, parabolic and hyperbolic cases. Eventually we try to describe some of the open questions for two other assumptions and future directions. This talk is based on arXiv:1108.0078 (published in CQG) and 1307.1378,gr (published in JCAP) in collaboration with Luis Alvarez-Gaume and some works in progress.
- 15/06/2016 (Wednesday), 2 - 4pm, DWB Conference Room: Jorge Casalderrey-Solana (Oxford): TBA
If you are interested in presenting your research in Oxford, please contact Jonas Probst.
For a list of past talks follow this link.
The following might also be of interest:
- A weekly updated list of talks related to string theory.
- A list of all seminars in the Physics Department, including the Theoretical Physics Colloquium and the Particles and Fields Seminar.