Drag force to all orders in gradients

Understand

We study the energy loss of a heavy quark slowly moving through an evolving strongly coupled plasma.

• We use the linearized fluid/gravity correspondence to describe small perturbations of the medium flow with general spacetime dependence.
• This all order linearized hydrodynamics results in a drag force exerted on a heavy quark even when it is at rest with the fluid element.
• We show how the general contribution to the drag force can be derived order by order in the medium velocity gradients and provide explicit results valid up to the third order.