Colliding shock waves and hydrodynamics in small systems

Understand

Using numerical holography, we study the collision of a planar sheet of energy with a bounded localized distribution of energy.

• The collision, which mimics proton-nucleus collisions, produces a localized lump of debris with transverse size $R \sim 1/T_{\rm eff}$ with $T_{\rm eff}$ the effective temperature, and has large gradients and large transverse flow.
• Nevertheless, the postcollision evolution is well described by viscous hydrodynamics.
• Our results bolster the notion that debris produced in proton-nucleus collisions may be modeled using hydrodynamics.