标题：Global and local polarization of A hyperons in Au plus Au collisions at 200 GeV from STAR
作者：Niida, Takafumi; Adam, J.; Adamczyk, L.; Adams, J. R.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; An 更多
作者机构：[Niida, Takafumi] Wayne State Univ, 666 W Hancock, Detroit, MI 48201 USA.; [Drachenberg, J. L.] Abilene Christian Univ, Abilene, TX 79699 USA.; [A 更多
会议名称：27th International Conference on Ultrarelativistic Nucleus-Nucleus Collisions (Quark Matter)
会议日期：MAY 13-19, 2018
来源：NUCLEAR PHYSICS A
摘要：New results on global polarization of A hyperons in Au+Au collisions at root s(NN) = 200 GeV reveal non-zero signal on the order of a few tenths of a percent. Compared with lower energy results, the current measurement shows that the polarization decreases at higher collision energy, the trend being well reproduced by theoretical calculations. The polarization is found to be larger in more peripheral collisions, as well as in the in-plane than in the out-of-plane direction. The signal seems to depend on the asymmetry between positive and negative charge in each event, which may indicate an influence of the axial current induced by the magnetic field. In addition, the first measurement of a local polarization along the beam direction was performed. The results show a quadrupole modulation relative to the second-order event plane, as expected from the elliptic flow.