Global polarization measurement in Au+Au collisions

The STAR collaboration
Phys.Rev.C 76 (2007) 024915, 2007.

Abstract (data abstract)
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 $\overline{\Lambda}$ hyperons in the STAR acceptance is consistent with zero within the precision of the measurements. The obtained upper limit, $|P_{\Lambda,\overline{\Lambda}}|$ <= 0.02, is compared to the theoretical values discussed recently in the literature.

  • Figure 2

    Data from Figure 2

    10.17182/hepdata.98581.v2/t1

    (Color online) Invariant mass distribution for the $\Lambda$ (filled circles) and $\overline{\Lambda}$ (open squares) candidates after the quality cuts for...

  • Figure 3

    Data from Figure 3

    10.17182/hepdata.98581.v2/t2

    (Color online) Global polarization of $\Lambda$–hyperons as a function of $\Lambda$ transverse momentum $p^{\Lambda}_{t}$. Filled circles show the results for...

  • Figure 4

    Data from Figure 4

    10.17182/hepdata.98581.v2/t3

    (Color online) Global polarization of $\Lambda$–hyperons as a function of $\Lambda$ pseudorapidity $\eta^{\Lambda}$. Filled circles show the results for Au+Au...

  • Figure 5

    Data from Figure 5

    10.17182/hepdata.98581.v2/t4

    (Color online) Global polarization of $\Lambda$–hyperons as a function of centrality given as fraction of the total inelastic hadronic cross...

  • Figure 6

    Data from Figure 6

    10.17182/hepdata.98581.v2/t5

    (Color online) Global polarization of $\overline{\Lambda}$–hyperons as a function of $\overline{\Lambda}$ transverse momentum $p^{\overline{\Lambda}}_{t}$. Filled circles show the results for...

  • Figure 7

    Data from Figure 7

    10.17182/hepdata.98581.v2/t6

    (Color online) Global polarization of $\overline{\Lambda}$–hyperons as a function of $\overline{\Lambda}$ pseudorapidity $\eta^{\overline{\Lambda}}$. Filled circles show the results for Au+Au...

  • Figure 8

    Data from Figure 8

    10.17182/hepdata.98581.v2/t7

    (Color online) Global polarization of $\overline{\Lambda}$–hyperons as a function of as a function of centrality. Filled circles show the results...

  • Figure 9 a

    Data from Figure 9 a

    10.17182/hepdata.98581.v2/t8

    (Color online) Acceptance correction function $A_{0}(p^{H}_{t}, \eta^{H})$ defined in (10) as a function of $\Lambda$ (filled circles) and $\overline{\Lambda}$ (open...

  • Figure 9 b

    Data from Figure 9 b

    10.17182/hepdata.98581.v2/t9

    (Color online) Acceptance correction function $A_{0}(p^{H}_{t}, \eta^{H})$ defined in (10) as a function of $\Lambda$ (filled circles) and $\overline{\Lambda}$ (open...

  • Figure 10 a

    Data from Figure 10 a

    10.17182/hepdata.98581.v2/t10

    (Color online) Function $A_{2}(p^{H}_{t}, \eta^{H})$ defined in (11) as a function of $\Lambda$ (filled circles) and $\overline{\Lambda}$ (open squares) transverse...

  • Figure 10 b

    Data from Figure 10 b

    10.17182/hepdata.98581.v2/t11

    (Color online) Function $A_{2}(p^{H}_{t}, \eta^{H})$ defined in (11) as a function of $\Lambda$ (filled circles) and $\overline{\Lambda}$ (open squares) transverse...

Version 2 modifications: See PHYSICAL REVIEW C 95, 039906(E) (2017): polarization parameters in Figs. 3-8 are plotted with wrong signs

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