Delocalizing Entanglement of Anisotropic Black Branes

We study the mutual information between pairs of regions on the two asymptotic boundaries of maximally-extended anisotropic black-brane solutions. This quantity characterizes the local pattern of entanglement of thermofield double states which are dual to these geometries. We analyse the disruption of the mutual information in anisotropic shock wave geometries and show that the entanglement velocity plays an important role in this phenomenon. Besides that we compute several chaos-related properties of this system, like the entanglement velocity, the butterfly velocity and the scrambling time. We find that the butterfly velocity and the entanglement velocity violate the upper bounds proposed in 1311.1200 and 1612.00082, but remain bounded by their corresponding values in the infrared effective theory.Comment: 34 pages, 10 figures. V2: typos corrected and references added. Analysis extended to higher anisotropies. Figures 3, 6(a) and 8(b) replaced to include higher anisotropies. Figures 6(b), 7(a) and 7(b) replaced to improve visualization. Minor changes in the end of the abstract and introduction. Two figures added in App. C. Discussion and App.C expanded. V3: Matches published versio

Definable henselian valuations

In this note we investigate the question whether a henselian valued field carries a non-trivial 0-definable henselian valuation (in the language of rings). It follows from the work of Prestel and Ziegler that there are henselian valued fields which do not admit a 0-definable non-trivial henselian valuation. We give conditions on the residue field which ensure the existence of a parameter-free definiton. In particular, we show that a henselian valued field admits a non-trivial 0-definable valuation when the residue field is separably closed or sufficiently non-henselian, or when the absolute Galois group of the (residue) field is non-universal.Comment: 14 pages, revised versio