Two theorems for the gradient expansion of relativistic hydrodynamics

Saulo Diles

doi:10.1016/j.physletb.2021.136850

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arXiv · 2012.00033

Two theorems for the gradient expansion of relativistic hydrodynamics

Saulo Diles

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Abstract

This letter is dedicated to providing proof of two statements concerning the gradient expansion of relativistic hydrodynamics. The first statement is that \textit{the ordering of transverse derivatives is irrelevant in the gradient expansion of a non-conformal fluid}. The second statement is that \textit{the longitudinal projection of the Weyl covariant derivative can be eliminated in the gradient expansion of a conformal fluid}. This second statement does not apply to curvature tensors. In the conformal case, we know that the ordering of Weyl covariant derivatives is irrelevant in the gradient expansion.

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Saulo Diles. 2022-01-05. Two theorems for the gradient expansion of relativistic hydrodynamics. https://doi.org/10.1016/j.physletb.2021.136850

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