Black brane entropy and hydrodynamics: the boost-invariant case

Understand

The framework of slowly evolving horizons is generalized to the case of black branes in asymptotically anti-de Sitter spaces in arbitrary dimensions.

• The results are used to analyze the behavior of both event and apparent horizons in the gravity dual to boost-invariant flow.
• These considerations are motivated by the fact that at second order in the gradient expansion the hydrodynamic entropy current in the dual Yang-Mills theory appears to contain an ambiguity.
• This ambiguity, in the case of boost-invariant flow, is linked with a similar freedom on the gravity side.