Global polarization of and hyperons has been measured for the first time in Au+Au collisions at sqrt[s_{NN}]=200GeV. The measurements of the ^{-} and [over ]^{+} hyperon polarization have been performed by two independent methods, via analysis of the angular distribution of the daughter particles in the parity violating weak decay +, as well as by measuring the polarization of the daughter hyperon, polarized via polarization transfer from its parent. The polarization, obtained by combining the results from the two methods and averaged over ^{-} and [over ]^{+}, is measured to be P_{}=0.470.10(stat)0.23(syst)% for the collision centrality 20%-80%. The P_{} is found to be slightly larger than the inclusive polarization and in reasonable agreement with a multiphase transport model. The P_{} is found to follow the centrality dependence of the vorticity predicted in the model, increasing toward more peripheral collisions. The global polarization of , P_{}=1.110.87(stat)1.97(syst)% was obtained by measuring the polarization of daughter in the decay +K, assuming the polarization transfer factor C_{}=1.
Phys Rev Lett
- 5107 Particle And High Energy Physics
- 5106 Nuclear And Plasma Physics
- 51 Physical Sciences
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