Colliding shock waves and hydrodynamics in small systems

TL;DR

This paper uses numerical holography to study energy collisions resembling proton-nucleus interactions, showing that the resulting debris can be effectively modeled by viscous hydrodynamics despite large gradients.

Contribution

It demonstrates that hydrodynamics accurately describes the postcollision evolution of debris in small systems using numerical holography.

Findings

Debris has a transverse size inversely proportional to effective temperature.

Postcollision evolution aligns with viscous hydrodynamics.

Hydrodynamics can model proton-nucleus collision debris effectively.

Abstract

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.