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Main Authors: Yi, Cong, Pu, Shi, Pang, Long-Gang, Qin, Guang-You, Wang, Xin-Nian
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2603.27521
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author Yi, Cong
Pu, Shi
Pang, Long-Gang
Qin, Guang-You
Wang, Xin-Nian
author_facet Yi, Cong
Pu, Shi
Pang, Long-Gang
Qin, Guang-You
Wang, Xin-Nian
contents Significant global polarization of $Λ$ hyperons along the direction of the orbital angular momentum has been measured in non-central heavy-ion collisions where the equation of state (EOS) of the produced dense matter is expected to change from intermediate to low colliding energies. We study the sensitivity of the global $Λ$ polarization to EOS in heavy-ion collisions within the SMASH transport model. Among the three different EOS we considered, only the hadron resonance gas (HRG) describes the experimental data well at low colliding energies even when it is below the $Λ$ production threshold in nucleon-nucleon collisions. The polarization induced by thermal vorticity as a function of centrality, rapidity, and transverse momentum at $\sqrt{s_{NN}} = 3$ GeV in Au+Au collisions is shown to agree well with the experimental data. Our study also indicates a possible peak in the global $Λ$ polarization around $\sqrt{s_{NN}} = 2.4$ GeV in Au+Au collisions. Furthermore, we find that the rapidity and transverse momentum-dependent helicity polarization induced by thermal vorticity vanishes due to space-reversal symmetry.
format Preprint
id arxiv_https___arxiv_org_abs_2603_27521
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Global polarization of $Λ$ hyperons and its sensitivity to equations of state in low-energy heavy-ion collisions
Yi, Cong
Pu, Shi
Pang, Long-Gang
Qin, Guang-You
Wang, Xin-Nian
Nuclear Theory
Significant global polarization of $Λ$ hyperons along the direction of the orbital angular momentum has been measured in non-central heavy-ion collisions where the equation of state (EOS) of the produced dense matter is expected to change from intermediate to low colliding energies. We study the sensitivity of the global $Λ$ polarization to EOS in heavy-ion collisions within the SMASH transport model. Among the three different EOS we considered, only the hadron resonance gas (HRG) describes the experimental data well at low colliding energies even when it is below the $Λ$ production threshold in nucleon-nucleon collisions. The polarization induced by thermal vorticity as a function of centrality, rapidity, and transverse momentum at $\sqrt{s_{NN}} = 3$ GeV in Au+Au collisions is shown to agree well with the experimental data. Our study also indicates a possible peak in the global $Λ$ polarization around $\sqrt{s_{NN}} = 2.4$ GeV in Au+Au collisions. Furthermore, we find that the rapidity and transverse momentum-dependent helicity polarization induced by thermal vorticity vanishes due to space-reversal symmetry.
title Global polarization of $Λ$ hyperons and its sensitivity to equations of state in low-energy heavy-ion collisions
topic Nuclear Theory
url https://arxiv.org/abs/2603.27521