Global and local polarization of Λ hyperons in Au+Au collisions at 200 GeV from STAR

Journal Article · Tue Jan 22 00:00:00 EST 2019 · Nuclear Physics. A

DOI:https://doi.org/10.1016/j.nuclphysa.2018.08.034· OSTI ID:1580368

Niida, Takafumi ^[1]

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1. Wayne State Univ., Detroit, MI (United States)

New results on global polarization of Λ hyperons in Au+Au collisions at √^sNN = 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.

• Research Organization: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Nuclear Physics (NP)
• Contributing Organization: STAR Collaboration
• Grant/Contract Number: AC02-05CH11231; FG02-92ER40713
• OSTI ID: 1580368
• Journal Information: Nuclear Physics. A, Vol. 982, Issue C; ISSN 0375-9474
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS