Initial fluctuation effect on harmonic flow in high-energy heavy-ion collisions

Within the framework of a multi-phase transport model, harmonic flows $v_n$ (n = 2, 3 and 4) are investigated for Au + Au collisions at $\sqrt{s_{NN}}$ = 200 GeV and Pb + Pb collisions at $\sqrt{s_{NN}}$ = 2.76 TeV. The event-by-event geometry fluctuations significantly contribute to harmonic flows. Triangular flow ($v_3$) originates from initial triangularity ($\epsilon_3$) and is developed by partonic interactions. The conversion efficiency ($v_n/\epsilon_n$) decreases with harmonic order and increases with partonic interaction cross section. A mass ordering in the low $p_T$ region and number of constitute quark scaling in the middle $p_T$ region seem to work roughly for $n$-th harmonic flows at both energies. All features of harmonic flows show similar qualitative behaviors at RHIC and LHC energies, which implies that the formed partonic matters are similar at the two energies.