Oxford Holography Group

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Holography Seminar

Time and place: Tue 2-4 pm, room 501 (Seminar Room), DWB (additional seminars and non-standard time/place are listed in bold)

Michaelmas Term 2016 Talks:

• 11/10/2016: Cindy Keeler (Niels Bohr Institute, Copenhagen): Partition Functions via Quasinormal Mode Methods: Spin, Product Spaces, and Boundary Conditions
  Material:
  Abstract: After a review of the quasinormal mode method for partition function calculation developed by Denef, Hartnoll, and Sachdev, we extend the method to fields with higher spin, to product spaces, and to spaces with non-Dirichlet boundary conditions. Finally, we speculate on the physical meaning of these non-physical-mass modes.
• 18/10/2016: Jonas Probst (U.Oxford): Second-Order Hydrodynamics and Universality in Non-Conformal Holographic Fluids
  Material: Paper, Slides
  Abstract: As the precise gravity duals of theories realised in nature are unknown, we are particularly interested in universal properties of holographic models which may apply to all strongly coupled field theories. At the level of second-order hydrodynamics one particular combination of transport coefficients, H = 2ητπ − 4λ1 − λ2, has been shown to vanish universally in conformal holographic fluids. In this talk, I will discuss our recent results on second-order transport and on the fate of H in holographic models without conformal symmetry. I will present new Kubo formulae for five second-order coefficients including H in non-conformal fluids and show how they can be applied to holographic models. Focusing on holographic RG flows triggered by an arbitrary scalar operator of dimension 3, our work demonstrates that the transport coefficients always satisfy 2ητπ − 2 (κ − κ∗) − λ2 = 0. I will describe our proof that H vanishes when taking into account leading non-conformal corrections and present numerical results which suggest that H vanishes regardless of conformal symmetry.
• 25/10/2016: Lata Kh Joshi (Indian Institute of Technology, Bombay): Time-dependent holographic spectral function
  Material: Paper

  Abstract: Using state/geometry map, we have proposed a method to find retarded propagator in generic non-equilibrium states. We discuss the spectral function of a scalar in a class of non-equilibrium states. This class is given in terms of AdS-Vaidya geometry with an arbitrary parameter characterizing the dual state transition from one thermal state to another due to a homogenous quench. In this talk, I will discuss different routes and patterns of thermalization under various scalar momenta and quench durations.
• 01/11/2016: Nick Poovuttikul (U. Leiden): On "universality" of transport phenomena in holography
  Abstract: In this talk, I will discuss transport phenomena in two classes of theories with holographic dual. In the first part, I will discuss systems where U(1) current is non-conserved due to anomaly and illustrate how one can show that the anomalous conductivities are non-renormalised in a large class of holographic RG flows. The holographic RG flow we considered is generated by arbitrary dilaton potentials and arbitrary higher derivative terms that do not break global symmetries, incorporating coupling constant corrections to the boundary theory in an expansion around infinite coupling. In the second part, I will focus on systems where translational symmetry is broken by slowly varying scalar fields and show that the bound shear viscosity/entropy density is violated. I will also discuss how to understand the violation in the language of forced fluid dynamics.
• 08/11/2016: Frederic Brunner: Glueball decay in gauge/gravity duality
  Material: Paper
  Abstract: I will speak about recent progress on glueballs and their decay in the Witten-Sakai-Sugimoto model, a top-down holographic construction of D4 and D8 branes that allows one to study glueballs and their interactions with pseudoscalar and vector mesons. I particular, I will discuss predictions for collider experiments, involving, among others, the identification of the lightest scalar glueball.
• 15/11/2016: No seminar
• 22/11/2016: Ioannis Iatrakis: Recent progress in holographic QCD in the Veneziano limit
  Abstract: In this talk we will introduce a bottom-up holographic model of QCD in the Veneziano limit and present recent progress. In the first part of the talk we use the model in order to study the classical interaction of QCD strings and their collectivization under certain conditions. The interaction of a multi-string system and its collectivization approximates central pA collisions and explains the appearance of collective behavior. Then, the electromagnetic sector of the model is analyzed and used to calculate the thermal photon emission in heavy-ion collisions. Finally, the model is studied in the presence of external magnetic field, B. The phase diagram is constructed as a function of B. It is also shown that, at high temperature and magnetic field, chiral symmetry is de-catalyzed as it is expected from lattice studies.
• 29/11/2016: Christiana Pantelidou (U. Barcelona): Holographic magnetisation density waves
  Abstract: The AdS/CFT correspondence is a very powerful tool for studying strongly coupled CFTs at finite temperature, commonly found in condensed matter physics. Focusing on such systems in the presence of an external magnetic field, certain holographic models are known to exhibit spontaneous breaking of translational invariance resulting in an inhomogeneous phase. In this talk, I will present results on the construction of novel black hole solutions dual to a holographic magnetisation density wave phase and I will discuss some of their properties.

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.