Hydrodynamic flow in small systems, or: "How the heck is it possible that a system emitting only a dozen particles can be described by fluid dynamics?"

Abstract

The "unreasonable effectiveness" of relativistic fluid dynamics in describing high energy heavy-ion and even proton-proton collisions are demonstrated and discussed. Several recent ideas of optimizing relativistic fluid dynamics for the specific challenges posed by such collisions will be presented, and some thoughts will be offered why the framework works better than originally expected. I will also address the unresolved question where exactly hydrodynamics breaks down, and why.

arXiv commentTalk presented at KRUGER-2018, Hazyview, Mpumalanga, South Africa, Dec. 3-8, 2018, to appear in the proceedings, published in the Open Access Journal of Physics: Conference Series (JPCS)

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• Collective flow and viscosity in relativistic heavy-ion collisions
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• Elliptic and triangular flow in event-by-event (3+1)D viscous hydrodynamics
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Cited by in corpus (23)

• Further developments of a multi-phase transport model for relativistic nuclear collisions
• Exact solutions and attractors of higher-order viscous fluid dynamics for Bjorken flow
• Non-conformal attractor in boost-invariant plasmas
• On non-conformal kinetic theory and hydrodynamics for Bjorken flow
• Temperature and fluid velocity on the freeze-out surface from $\pi$, $K$, $p$ spectra in pp, p--Pb and Pb--Pb collisions
• Hydrodynamics from free-streaming to thermalization and back again
• Progress and Challenges in Small Systems
• Entropy production in pp and Pb-Pb collisions at energies available at the CERN Large Hadron Collider
• Conformal Bjorken flow in the general frame and its attractor: Similarities and discrepancies with the Müller-Israel-Stewart formalism
• Thermal photons as a sensitive probe of $\alpha$-cluster in C+Au collisions at the BNL Relativistic Heavy Ion Collider
• Hydrodynamic generators in relativistic kinetic theory
• System size dependence of the hadronic rescattering effect at energies available at the CERN Large Hadron Collider
• Hanbury Brown--Twiss Interferometry and Collectivity in Small Systems
• Using the non-hydrodynamic mode to study the onset of hydrodynamic behavior in ultraperipheral symmetric nuclear collisions
• Two-particle transverse momentum correlations in pp and p-Pb collisions at energies available at the CERN Large Hadron Collider
• Metric anisotropies and nonequilibrium attractor for expanding plasma
• The Multiplicity Dependence of Pion Interferometry in Hydrodynamics
• Testing the collectivity in large and small colliding systems with test particles
• Left-right splitting of elliptic flow due to directed flow in heavy ion collisions
• Long-range azimuthal correlations for partially coherent pion emission in proton-proton collisions
• Event-shaped-dependent cumulants in p-Pb collisions at 5.02 TeV
• Finite $V_{2\Delta }$ puzzle in low-multiplicity pp collisions from ultra-long-range azimuthal correlations in the string-shoving model
• Longitudinal Dynamics of Large and Small Systems from a 3D Bayesian Calibration of RHIC Top-energy Collision Data