Probing the high-density nuclear symmetry energy with the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msup><mml:mi mathvariant="normal">Ξ</mml:mi><mml:mo>−</mml:mo></mml:msup><mml:mo>/</mml:mo><mml:msup><mml:mi mathvariant="normal">Ξ</mml:mi><mml:mn>0</mml:mn></mml:msup></mml:mrow></mml:math> ratio in heavy-ion collisions at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msqrt><mml:msub><mml:mi>s</mml:mi><mml:mrow><mml:mi>N</mml:mi><mml:mi>N</mml:mi></mml:mrow></mml:msub></mml:msqrt><mml:mo>≈</mml:mo><mml:mn>3</mml:mn></mml:mrow></mml:math> GeV
Gao-Chan Yong, Bao-An Li, Zhigang Xiao, Zi-Wei Lin
Abstract
Recent beam energy scan experiments at the BNL Relativistic Heavy Ion Collider by the STAR Collaboration [Phys. Lett. B 827, 137003 (2022) and Phys. Rev. Lett. 128, 202303 (2022)] found that hadronic interactions dominate the collective flow and the proton cumulant ratios are driven by baryon number conservation in a region of high baryon density in $\sqrt{{s}_{NN}}=3$ GeV $\mathrm{Au}+\mathrm{Au}$ reactions, indicating that the dense medium formed in such collisions is likely hadronic matter. Within an updated a relativistic transport model with momentum dependent isoscalar and isovector single-nucleon mean-field potentials corresponding to different symmetry energies at suprasaturation densities, the $n/p, {\ensuremath{\pi}}^{\ensuremath{-}}/{\ensuremath{\pi}}^{+}, {K}_{s}^{0}/{K}^{+}, {\mathrm{\ensuremath{\Sigma}}}^{\ensuremath{-}}/{\mathrm{\ensuremath{\Sigma}}}^{+}$, and ${\mathrm{\ensuremath{\Xi}}}^{\ensuremath{-}}/{\mathrm{\ensuremath{\Xi}}}^{0}$ ratios are studied for central $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{{s}_{NN}}=3$ GeV, where the maximum central density reaches about $(3.6--4.0){\ensuremath{\rho}}_{0}$. The doubly strange ${\mathrm{\ensuremath{\Xi}}}^{\ensuremath{-}}/{\mathrm{\ensuremath{\Xi}}}^{0}$ ratio is found to have the strongest sensitivity to the variation of high-density nuclear symmetry energy. Thus, the ${\mathrm{\ensuremath{\Xi}}}^{\ensuremath{-}}/{\mathrm{\ensuremath{\Xi}}}^{0}$ ratio in relativistic heavy-ion reactions at $\sqrt{{s}_{NN}}\ensuremath{\sim}3$ GeV may help probe sensitively the poorly known symmetry energy of dense neutron-rich matter critically important for understanding various properties of neutron stars.