A Fourier-cumulant analysis for multiharmonic flow fluctuation: by employing a multidimensional generating function...

Area of Science:

• Nuclear Physics
• High-Energy Physics
• Quantum Chromodynamics

Background:

• Heavy-ion collisions are crucial for understanding the quark-gluon plasma.
• Analyzing particle distribution fluctuations probes the collective behavior of matter under extreme conditions.
• Event-by-event cumulant studies of Fourier coefficients are key to testing theoretical models.

Purpose of the Study:

• To develop a novel method for extracting and classifying multiharmonic flow fluctuations.
• To quantify higher-order cumulants and their dependence on harmonic orders.
• To compare theoretical predictions with experimental data and explore hydrodynamic response.

Main Methods:

• Utilizing a multidimensional generating function to extract cumulants of multiharmonic flow fluctuations.
• Performing hydrodynamic simulations (T$$ENTo+VISH2+1+UrQMD) for lead-lead (Pb-Pb) collisions.
• Calculating normalized cumulants and comparing them with Large Hadron Collider (LHC) measurements.

Main Results:

• Identified 33 distinct cumulants across orders 2-5 and harmonics 2-5.
• Computed normalized cumulants from simulations and compared them with LHC data.
• Calculated linear and nonlinear hydrodynamic response couplings by comparing initial and final state fluctuations.
• Introduced a genuine three-particle correlation function for third-order cumulant information.

Conclusions:

• The proposed method effectively extracts and classifies multiharmonic flow fluctuations.
• The study validates hydrodynamic models against LHC data and predicts unmeasured cumulants.
• Hydrodynamic response couplings were quantified, offering insights into the system's evolution.
• The new correlation function provides a comprehensive tool for analyzing third-order cumulants.