J. Adam, Creighton University
L. Adamczyk, AGH University of Science and Technology, Poland
J. R. Adams, Ohio State University
James K. Adkins, University of KentuckyFollow
G. Agakishiev, Joint Institute for Nuclear Research, Russia
M. M. Aggarwal, Panjab University, India
Z. Ahammed, Variable Energy Cyclotron Centre, India
N. N. Ajitanand, State University of New York - Stony Brook
I. Alekseev, Alikhanov Institute for Theoretical and Experimental Physics, Russia
D. M. Anderson, Texas A & M University
R. Aoyama, University of Tsukuba, Japan
A. Aparin, Joint Institute for Nuclear Research, Russia
D. Arkhipkin, Brookhaven National Laboratory
E. C. Aschenauer, Brookhaven National Laboratory
M. U. Ashraf, Tsinghua University, China
F. Atetalla, Kent State University
A. Attri, Panjab University, India
G. S. Averichev, Joint Institute for Nuclear Research, Russia
X. Bai, Central China Normal University, China
V. Bairathi, National Institute of Science Education and Research, India
K. Barish, University of California - Riverside
A. J. Bassill, University of California - Riverside
A. Behera, State University of New York - Stony Brook
R. Bellwied, University of Houston
A. Bhasin, University of Jammu, India
A. K. Bhati, Panjab University, India
J. Bielcik, Czech Technical University in Prague, Czech Republic
J. Bielcikova, Nuclear Physics Institute AS CR, Czech Republic
L. C. Bland, Brookhaven National Laboratory
I. G. Bordyuzhin, Alikhanov Institute for Theoretical and Experimental Physics, Russia
Renee H. Fatemi, University of KentuckyFollow
Suvarna Ramachandran, University of KentuckyFollow


Global polarization of Λ hyperons has been measured to be of the order of a few tenths of a percentage in Au+Au collisions at √sNN = 200 GeV, with no significant difference between Λ and Λ ̄. These new results reveal the collision energy dependence of the global polarization together with the results previously observed at √sNN = 7.7–62.4 GeV and indicate noticeable vorticity of the medium created in noncentral heavy-ion collisions at the highest Relativistic Heavy Ion Collider collision energy. The signal is in rough quantitative agreement with the theoretical predictions from a hydrodynamic model and from a multi-phase transport model. The polarization is larger in more peripheral collisions, and depends weakly on the hyperon's transverse momentum and pseudorapidity ηH within |ηH| < 1. An indication of the polarization dependence on the event-by-event charge asymmetry is observed at the 2σ level, suggesting a possible contribution to the polarization from the axial current induced by the initial magnetic field.

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Published in Physical Review C, v. 98, issue 1, 014810, p. 1-10.

©2018 American Physical Society

The copyright holder has granted the permission for posting the article here.

Due to the large number of authors, only the first 30 and the authors affiliated with the University of Kentucky are listed in the author section above. For the complete list of authors, please download this article or visit:

This group of authors is collectively known as the STAR Collaboration.

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This work was supported in part by the Office of Nuclear Physics within the U.S. DOE Office of Science; the U.S. National Science Foundation; the Ministry of Education and Science of the Russian Federation; National Natural Science Foundation of China; Chinese Academy of Science; the Ministry of Science and Technology of China and the Chinese Ministry of Education; the National Research Foundation of Korea; Czech Science Foundation and Ministry of Education, Youth and Sports of the Czech Republic; Department of Atomic Energy and Department of Science and Technology of the Government of India; the National Science Centre of Poland; the Ministry of Science, Education and Sports of the Republic of Croatia; RosAtom of Russia and German Bundesministerium fur Bildung, Wissenschaft, Forschung and Technologie (BMBF); and the Helmholtz Association.

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