RG Flow and Thermodynamics of Causal Horizons in AdS

Causal horizons in pure Poincare $AdS$ are Killing horizons generated by dilatation vector. Renormalization group (RG) flow breaks the dilatation symmetry and makes the horizons dynamical. We propose that the boundary RG flow is dual to the thermodynamics of the causal horizon. As a check of our proposal we show that the gravity dual of the boundary $c$-theorem is the second law of thermodynamics obeyed by causal horizons. The holographic $c$-function is the Bekenstein-Hawking entropy (density) of the dynamical causal horizon. We explicitly construct the $c$-function in a generic class of RG-flow geometries and show that it interpolates monotonically between the UV and IR central charges as a result of the second law.Comment: 15 pages, Latex, references added, figures added , relation to causal holographic information clarified, version accepted for publication in JHEP, references adde

Wess-Zumino Consistency Condition for Entanglement Entropy

In this brief note, we consider the variation of the entanglement entropy of a region as the shape of the entangling surface is changed. We show that the variation satisfies a Wess-Zumino like integrability condition in field theories which can be consistently coupled to gravity. In this case the "anomaly" is localized on the entangling surface. The solution of the integrability condition should give all the nontrivial finite local terms which can appear in the variation of the entanglement entropy.Comment: 14 pages, presentation improve