Transient Fluid Dynamics of the Quark-Gluon Plasma According to AdS/CFT

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We argue, using the AdS/CFT correspondence, that the transient dynamics of the shear stress tensor in a strongly coupled $\mathcal{N}=4$ SYM plasma is not described by relaxation-type, fluid dynamical equations: at long times the equations of motion should contain a \textit{second-order} comoving derivative of the shear stress tensor.

• This occurs because in this strongly-coupled system the lowest "non-hydrodynamical" quasinormal modes associated with shear stress possess a nonzero real part at zero wavenumber.
• We use Weyl invariance to obtain the most general equations of motion containing 2 comoving derivatives of the shear stress tensor in the transient regime that are compatible with the symmetries.
• We show that the asymptotic solution of this theory valid at times much larger than the timescale associated with the "non-hydrodynamical" modes reproduces the well-known results previously obtained directly from the AdS/CFT correspondence.