Forward-backward elliptic anisotropy correlation in parton cascade

A potential experimental probe, forward-backward elliptic anisotropy correlation ($C_{FB}$), has been proposed by Liao and Koch to distinguish the jet and true elliptic flow contribution to the measured elliptic flow ($v_2$) in relativistic heavy-ion collisions. Jet and flow fluctuation contribution to elliptic flow is investigated within the framework of a multi-phase transport model using the $C_{FB}$ probe. We found that the $C_{FB}$ correlation is remarkably different and is about two times of that proposed by Liao and Koch. It originates from the correlation between fluctuation of forward and backward elliptic flow at low transverse momentum, which is mainly due to the initial correlation between fluctuation of forward and backward eccentricity. This results in an amendment of the $C_{FB}$ by a term related to the correlation between fluctuation of forward and backward elliptic flow. Our results suggest that a suitable rapidity gap for $C_{FB}$ correlation studies should be around $\pm$ 3.5.