Oxford Holography Group

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• Oxford micro-workshop on analytic properties of thermal correlators - March 2017
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Holography Seminar

Time and place: Tue 2-4 pm, Fisher Room, DWB (additional seminars and non-standard time are listed in bold)

Hilary Term 2017 Talks:

• 16/01/2017 (Non-Standard Time & Location: 5-7 pm, Fisher room, DWB): Rodrigo Olea (UNAB, Chile): Kounterterms in AdS Gravity
  Material:
  Abstract: As an alternative to the holographic renormalization procedure in the context of AdS/CFT correspondence, we introduce a regularization scheme for AdS gravity based on the addition of boundary terms which are a given polynomial of the extrinsic and intrinsic curvatures (Kounterterms). These terms are closely related to either topological invariants or Chern-Simons densities in the corresponding dimension, they can be easily generalized to other gravity theories (Einstein-Gauss-Bonnet, Lovelock, etc.). We provide a general prescription on how to obtain standard holographic quantities at the boundary. We also briefly comment on a possible relation to supersymmetry.
• 17/01/2017: Roman Konoplya (U. Tubingen): Instabilities and quasinormal modes of black holes in the Einstein-Gauss-Bonnet theory
  Material: Paper
  Abstract: We review various gravitational instabilities of black holes which occur in Gauss-Bonnet theory. In asymptotically flat and anti-de Sitter case, there is the so-called eikonal instability, which occurs at high mutlipole numbers l and is accompanied by the breakdown of the well-defined initial value problem. In the de Sitter case, in addition to the eikonal instability, there is lowest l) instability owing to the non-zero positive lambda term. In the AdS case the system approaches the threshold of instability "through" the purely imaginary modes. We show that all small Gauss-Bonnet-AdS black holes are unstable. Recently, through the analysis of critical behavior in AdS spacetime in the presence of GB term, it was shown [N. Deppe et. al PRL114, 071102 (2015)] that if the total energy content of the AdS spacetime is small, no black holes can be formed with mass less than some critical value. The found here instability of all small GB-AdS black holes may explain the existing mass gap in their formation.
• 24/01/2017: No Seminar
• 31/01/2017: Carlos Hoyos (Oviedo): Neutron stars and speed limits in AdS/CF
  Material: Paper 1, Paper 2
  Abstract: The properties of matter in the interior of neutron stars cannot be described from first principles using perturbation theory or lattice calculations. It is even unknown whether deconfined matter could exist at the core of the star. We examine this question in different holographic models of deconfined matter and discuss how constraints on equations of state of holographic models might affect the results.
• 07/02/2017: No Seminar
• 14/02/2017: Francesco Nitti (U. Paris Diderot): Exotic RG flows from holography
  Abstract: I will discuss the general structure of holographic renormalization group (RG) flow solutions in Einstein gravity coupled to one scalar field, dual to field theory RG flows driven by a single relevant coupling. I will review the standard solutions interpolating between UV and and IR asymptotically AdS geometries, then discuss recently discovered more exotic solutions, which have no obvious analog in weakly coupled field theories. Some of these are RG flows which skip an intermediate conformal fixed point. Others are solution in which the flow of the coupling reverses its direction. I will discuss the field theory interpretation of these geometries, and possible implications for holographic c-theorems.
• 21/02/2017: No Seminar
• 28/02/2017: Wilke van der Schee (MIT): Recent holographic heavy ion collisions: jets and hydrodynamisation
  Material: Paper 1, Paper 2 , Slides
  Abstract: This talk aims to give an accessible overview of recent progress on employing holography to better understand the creation of quark-gluon plasma in heavy ion collisions. This includes the fast approach to hydrodynamics, now called hydrodynamisation. Recently this has been extended to collisions within Einstein-Gauss-Bonnet gravity, which can mimic quantum field theories with a finite coupling constant. Lastly, we highlight an improved understanding of jets traversing the plasma, whereby we combine perturbative QCD for the creation of jets and subsequently propagate these jets in a holographic framework. This allows to study modifications of the shape of jets due to the presence of the quark-gluon plasma.
• 6-8/03/2017: Oxford micro-workshop on analytic properties of thermal correlators - March 2017

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.