Abstract
The presence of large event-by-event flow fluctuations in heavy ion collisions at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC) provides an opportunity to study a broad class of flow observables. This paper explores the correlations among harmonic flow coefficients and their phases , as well as the rapidity fluctuation of . The study is carried out using the Pb + Pb events generated by the multiphase transport (AMPT) model with fixed impact parameter. The overall ellipticity or triangularity of events is varied by selecting on the eccentricities or the magnitudes of the flow vector in a subevent for and 3, respectively. The responses of the harmonic coefficients, the event-plane correlations, and the rapidity fluctuations to the change in and are then systematized. Strong positive correlations are observed among all even harmonics , , and (all increase with ), between and (both increase with ), and between and (both increase with ), consistent with the effects of nonlinear collective response. In contrast, an anticorrelation is observed between and similar to that seen between and . These correlation patterns are found to be independent of whether selecting on or , validating the ability of in selecting the initial geometry. A forward/backward asymmetry of is observed for events selected on but not on , reflecting dynamical fluctuations exposed by the selection. Many event-plane correlators show good agreement between and selections, suggesting that their variations with are controlled by the change of in the initial geometry. Hence these correlators may serve as promising observables for disentangling the fluctuations generated in various stages of the evolution of the matter created in heavy ion collisions.
13 More- Received 11 December 2013
- Revised 22 July 2014
DOI:https://doi.org/10.1103/PhysRevC.90.024910
©2014 American Physical Society