Collision-System and Beam-Energy Dependence of Anisotropic Flow Fluctuations

Area of Science:

• Nuclear Physics
• High-Energy Physics
• Quantum Chromodynamics

Background:

• Understanding the behavior of matter under extreme conditions, such as the quark-gluon plasma (QGP), is crucial in nuclear physics.
• Heavy-ion collisions provide a unique environment to study the QGP and its properties.
• Flow fluctuations offer insights into the initial state and dynamics of these collisions.

Purpose of the Study:

• To investigate the origins of flow fluctuations in various heavy-ion collision systems.
• To determine the dependence of flow fluctuations on collision centrality, system size, particle species, and beam energy.
• To compare experimental results with theoretical models and simulations.

Main Methods:

• Utilizing multi-particle (two-, four-, and six-particle) correlation techniques to measure elliptic flow.
• Analyzing data from Uranium-Uranium (U+U), Copper-Gold (Cu+Au), and Gold-Gold (Au+Au) collisions across a range of beam energies (sqrt[s_{NN}]=11.5-200 GeV).
• Comparing experimental measurements with theoretical predictions from viscous hydrodynamics and the Trento model.

Main Results:

• Flow fluctuations exhibit a strong dependence on collision centrality.
• A modest dependence of flow fluctuations on system size was observed.
• Little to no dependence on particle species or beam energy was found.
• Experimental results align with theoretical models suggesting initial-state fluctuations dominate.

Conclusions:

• Initial-state fluctuations play a predominant role in generating the observed flow fluctuations in heavy-ion collisions.
• The findings contribute to a deeper understanding of the initial conditions and dynamics of the quark-gluon plasma.
• Further studies can refine models and explore other observables to probe the early stages of heavy-ion collisions.