Week 23.11.2014 – 29.11.2014

We classify the possible linear unfolded equations for propagating bosonic higher-spin tensor fields in AdS_3 backgrounds. Doing this we reproduce the existing topologically massive and new topologically massive (higher)-spin systems whose content we clarify. We find systems that generalise various critical gravities to higher-spins.

It is widely believed that hydrodynamics is the low energy effective theory of any quantum field theory. In this talk I will derive the local low energy effective action for uncharged dissipationless conformal fluids through holography. This can be achieved by solving a double-Dirichlet problem for linearised gravitational perturbations between the conformal boundary of a (4+1)-dimensional AdS-black brane background and a stretched horizon. Interestingly dissipationless fluid dynamics is captured by Goldstone bosons of the broken symmetries by the classical solution ending on the second boundary. I will discuss how the effective action approach might be inconsistent unless there is a coupling to a dissipative dynamical IR sector which for simplicity can be replaced by a membrane paradigm-like boundary condition on a stretched horizon and I will also comment on the limits of validity of this simplification.

We determine the most general three-dimensional vacuum spacetime with a negative cosmological constant containing a non-singular Killing horizon. We show that the general solution with a spatially compact horizon possesses a second commuting Killing field and deduce that it must be related to the BTZ black hole (or its near-horizon geometry) by a diffeomorphism. We show there is a general class of asymptotically AdS_3 extreme black holes with arbitrary charges with respect to one of the asymptotic-symmetry Virasoro algebras and vanishing charges with respect to the other. We interpret these as descendants of the extreme BTZ black hole.

Is there a consistent patching for double manifolds? I shall demonstrate that the solution of the strong section condition leads to exact 3-form field strengths. I shall also prove that the consistency of the examples presented so far depends on the choice of the atlas, and so they are not general covariant. Then I shall suggest a new construction which resolves some of the puzzles and possibly specifies the appropriate spaces up to homotopy.

It is commonly believed that for a quantum field theory to be fundamental, its high-energy behaviour must be governed by an ultraviolet (UV) fixed point. A very satisfying example is given by asymptotic freedom of QCD where the UV fixed point is non-interacting. In this talk, I discuss the existence of interacting UV fixed points in various quantum field theories, in particular in four dimensions, both with and without gravity. Implications for particle physics are also evaluated.