Global polarization measurement in Au+Au collisions

The system created in non-central relativistic nucleus-nucleus collisions possesses large orbital angular momentum. Due to spin-orbit coupling, particles produced in such a system could become globally polarized along the direction of the system angular momentum. We present the results of Lambda and anti-Lambda hyperon global polarization measurements in Au+Au collisions at sqrt{s_NN}=62.4 GeV and 200 GeV performed with the STAR detector at RHIC. The observed global polarization of Lambda and anti-Lambda hyperons in the STAR acceptance is consistent with zero within the precision of the measurements. The obtained upper limit, |P_{Lambda,anti-Lambda}| <= 0.02, is compared to the theoretical values discussed recently in the literature.

Note:

11 pages, 10 figures, 1 table, minor changes, accepted for publication in Phys. Rev. C

24.70.+s
25.75.Ld
14.20.Jn
nucleus nucleus: colliding beams
scattering: heavy ion
gold
Lambda: hadroproduction
Lambda: hadronic decay
angular distribution
Lambda: polarization

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