2-particle correlation analysis with Spherical Harmonics

The collective behavior of particles created in high-energy collisions is typically studied using azimuthal asymmetries between different particles or the reaction plane of the event. These correlations expressed in Fourier compositions have been studied in several hydrodynamics and other approaches. Recent observations of collectivity even in small systems pose challenges on the true sources of the collectivity behavior. We propose the use of 3-D Spherical Harmonics to simultaneously quantify azimuthal and rapidity of asymmetries in particle correlations, providing additional information on particle collectivity. This presentation is going to report the updated analysis of using the 2-particle correlation to study collectivity in both PYTHIA and AMPT (A Multi-Phase Transport) event generator models.