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$\phi$-meson production in Au + Au collisions at $\sqrt{s_{_{\rm NN}}}$ = 3\ GeV from STAR

ORAL

Abstract

$\phi$-meson is the lightest bound state of strange quarks($s\overline{s}$). It has relatively small hadronic interaction cross sections, therefore $\phi$-meson is considered to be a sensitive probe of the earlier dynamics in the heavy-ion collision. Recent measurements by HADES and FOPI on subthreshold $\phi$-meson production show a larger $\phi/K^{-}$ ratio compared to the results at higher energies[1,2], and this larger $\phi/K^{-}$ ratio cannot be described by thermal model calculations with Grand Canonical Ensemble for strangeness. In this presentation, we will report on our first measurements of $\phi$-meson production in Au+Au collisions at $\sqrt{s_{_{\rm NN}}}$ = 3$\ $GeV with energy just above the NN threshold. The data were taken in 2018 by the STAR experiment with Fixed Target configuration. $\phi$-mesons are measured through their hadronic decay channel, $\phi\rightarrow K^-+K^+$. After being corrected for the detector acceptance and tracking efficiencies, invariant yields of $\phi$-mesons as well as $\phi/K^{-}$ ratio are presented in several centrality intervals and the results will compared to model calculations. \\ [1] HADES Collaboration, Phys. Let. {\bf B 778}, (2018) 403-407. \\ [2] FOPI Collaboration, Eur. Phys. J. {\bf A 52}, (2016) 177.

Authors

  • Guannan Xie

    Lawrence Berkeley National Laboratory