Longitudinal flow decorrelation in heavy-ion collision at RHIC energies using a multi-phase transport model

Abstract

We present a study on the longitudinal flow decorrelation in heavy-ion collisions at the RHIC Beam Energy Scan (BES) energies ($\sqrt{s_{NN}}$ = 11.5 to 200 GeV in Au+Au collisions) using the AMPT model. We measure the second and third order factorization ratios ($r_2$ and $r_3$) across BES energies, finding $r_2$ weakly dependent on collision energy while $r_3$ shows a more prominent collision energy dependent. The effect of parton-parton scattering cross section on $r_2$ and $r_3$ is studied which suggests that longitudinal decorrelation could be a potential observable to constrain transport properties of the medium. We also analyze the contributions of flow-plane and flow magnitude decorrelation, with flow-plane decorrelation being dominant. we measure a recently proposed observable, the four particle cumulant ($T_2$), which remains resilient to non-flow effects and exhibits sensitivity to different decorrelation patterns. Through the measurement of $T_2$, we consistently observe a hint of S-shaped or torqued decorrelation across all energy ranges in peripheral collisions (40-80\%). But in central and mid-central collisions, presence of any specific pattern of decorrelation is missing in AMPT model.

Comments: 8 pages, 8 figures