Final state effects on charge asymmetry of pion elliptic flow in high-energy heavy-ion collisions

Within a multi-phase transport (AMPT) model with the string melting mechanism and imported initial electric quadrupole moment, the difference between the elliptic flow of positive and negative pions is calculated. The slope parameter $r$ of the linear dependence of $\Delta v_{2}=v_{2}(\pi^{-})-v_{2}(\pi^{+})$ on $A_{ch}=(N^{+}-N^{-})/(N^{+}+N^{-})$ is yielded owing to the parton cascade, which converts the initial electric quadrupole distribution into the final charge-dependent elliptic flow. The slope parameter $r$ is found to be increased by the hadronization given by the coalescence, and decreased by the resonance decays. The slope parameter $r$ is very sensitive to both the initial electric quadrupole percentage and centrality bin and consequently a helpful constraint on the quadrupole moment of the chiral magnetic wave is obtained for Au+Au collisions at the top RHIC energy.Comment: 4 pages, 4 figures, 1 table, final published versio

Towards detailed tomography of high energy heavy-ion collisions by γ\gamma-jet

Within a multi-phase transport (AMPT) model with string melting scenario, the transverse momentum imbalance between prompt photon and jet is studied in Pb+Pb collisions at $\sqrt{s_{_{\rm NN}}}$ = 2.76 TeV. Jet loses more energy in more central collisions due to strong partonic interactions between jet parton shower and partonic matter, which is more significant than due to hadronic interactions only. The hadronization and final-state hadronic interactions have little influences on the imbalance. The imbalance ratio $x_{j\gamma}$ is sensitive to both production position and passing direction of $\gamma$-jet, which provides an opportunity to do detail $\gamma$-jet tomography on the formed partonic matter by selecting different $x_{j\gamma}$ ranges. It is also proposed that $\gamma$-hadron azimuthal correlation associated with photon+jet is a probe to see the medium responses to different $\gamma$-jet production configurations.Comment: 5 pages, 4 figures, final published versio