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Search: authors:"Anastasios C. Petkou"

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Flat holography and Carrollian fluids

Abstract We show that a holographic description of four-dimensional asymptotically locally flat spacetimes is reached smoothly from the zero-cosmological-constant limit of anti-de Sitter holography. To this end, we use the derivative expansion of fluid/gravity correspondence. From the boundary perspective, the vanishing of the bulk cosmological constant appears as the zero...

The analytic structure of conformal blocks and the generalized Wilson-Fisher fixed points

We describe in detail the method used in our previous work arXiv:​1611.​10344 to study the Wilson-Fisher critical points nearby generalized free CFTs, exploiting the analytic structure of conformal blocks as functions of the conformal dimension of the exchanged operator. Our method is equivalent to the mechanism of conformal multiplet recombination set up by null states. We...

The free σCFTs

We introduce the conformal field theories that describe the shadows of the lowest dimension composites made out of massless free scalars and fermions in d dimensions. We argue that these theories can be consistently defined as free CFTs for even d ≥ 4. We use OPE techniques to study their spectrum and show that for d → ∞ it matches that of free bosonic CFTs in d = 6 and d = 4...

Instantons and the Hartle-Hawking-Maldacena proposal for dS/CFT

We test the Maldacena proposal for the Hartle-Hawking late time quantum state in an asymptotically de Sitter universe. In particular, we calculate the on-shell action for scalar instantons on the southern hemisphere of the four-sphere and compare the result with the renormalized on-shell action for scalar instantons in EAdS4. The two results agree provided the corresponding...

Petrov classification and holographic reconstruction of spacetime

Using the asymptotic form of the bulk Weyl tensor, we present an explicit approach that allows us to reconstruct exact four-dimensional Einstein spacetimes which are algebraically special with respect to Petrov’s classification. If the boundary metric supports a traceless, symmetric and conserved complex rank-two tensor, which is related to the boundary Cotton and energy-momentum...

Holographic perfect fluidity, Cotton energy-momentum duality and transport properties

We investigate background metrics for 2 + 1-dimensional holographic theories where the equilibrium solution behaves as a perfect fluid, and admits thus a thermodynamic description. We introduce stationary perfect-Cotton geometries, where the Cotton-York tensor takes the form of the energy-momentum tensor of a perfect fluid, i.e. they are of Petrov type Dt. Fluids in equilibrium...

Holographic fluids with vorticity and analogue gravity

We study holographic three-dimensional fluids with vorticity in local equilibrium and discuss their relevance to analogue gravity systems. The Fefferman-Graham expansion leads to the fluid’s description in terms of a comoving and rotating Papapetrou- Randers frame. A suitable Lorentz transformation brings the fluid to the non-inertial Zermelo frame, which clarifies its...