Study of Longitudinal Event-plane Decorrelation in Heavy-ion Collisions with a Multiphase Transport Model
Abstract
Measurements of pseudorapidity (η) dependence of local event-plane (EP) correlations provide novel inputs to the initial conditions in heavy-ion collisions. A factorization ratio of elliptic flow (v2), r2(η) = «v2(- η) cos [ 2(Ψm , - η -Ψf) ] » / «v2(η) cos [ 2(Ψm , η -Ψf) ] » , has been extensively used to quantify the decorrelation between two EPs at midrapidities (Ψm , +/- η) using a forward EP (Ψf) as a reference. However, nonflow effects could cause features in r2 similar to decorrelation. In this study, we shall employ a multiphase transport model (AMPT) to evaluate the sensitivity of several methods to both decorrelation and nonflow. Differential measurements of r2(η) and its slope, F2, as well as their modified forms indicated possible nonflow effect contribution. We propose an alternative observable, T2 = « sin(2(Ψf -Ψm , 1)) sin(2(Ψb -Ψm , 2)) » , which has different sensitivity to dynamics of decorrelation from twist of initial participant matter and/or nonflow effect. We employ event-shape selection analysis technique to investigate features in F2 and T2, and discuss their physics implications.
- Publication:
-
APS Division of Nuclear Physics Meeting Abstracts
- Pub Date:
- 2020
- Bibcode:
- 2020APS..DNP.FC005X