arXiv subjects

Yu-Liang Zhao

Publications and source records attributed to Yu-Liang Zhao.

3 recordsLinked to original sources

arXiv2026

Proton Collectivity in Au+Au Collisions at $\sqrt{s_{\rm NN}}=2.4-4.5$~GeV from a Unified Purely Hadronic EOS without QCD Phase Transition

The nuclear equation of state (EOS) is generally considered to soften in the density range of $2-5$ times the saturation density $\rho_0$. Using a purely hadronic transport model, we calculate the proton directed, sideward, and elliptic flows and their excitation functions in heavy-ion collisions (HICs) at $\sqrt{s_{\rm NN}}=2.4-4.5$~GeV and compare with the HADES, E895, and STAR data. We find that a momentum-dependent mean field with a unified incompressibility $K_0=230$~MeV quantitatively reproduces the experimental proton flows up to 4.3 GeV, at which the maximum density reaches approximately $5\rho_0$. At 4.5 GeV, however, the pure hadronic model fails to reproduce the proton directed and elliptic flow data, providing circumstantial evidence for the onset of partonic degrees of freedom in HICs. Our results provide a hadronic baseline to characterize the high-density nuclear matter and to map the region of hadron-quark phase transition.

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arXiv2026

Proton and kaon production in Au+Au collisions at $\sqrt{s_{\rm NN}}=3$ GeV

Within an extended isospin- and momentum-dependent Boltzmann-Uehling-Uhlenbeck transport model, we study the protons, $K^+$ mesons and $\Lambda$ hyperons production in Au+Au collisions at $\sqrt{s_{\rm NN}}=3$ GeV. For the collision in 0-10% centrality, we study the transverse momentum spectra and rapidity dependent mean transverse momentum for protons. For the collision in 10-40% centrality, we study the directed and elliptic flows for protons and $K^+$ mesons. The results show that the momentum-dependent nuclear mean field with an incompressibility $K_0=230$ MeV can fit fairly the STAR experimental data, while the momentum-independent nuclear mean field with both $K_0=230$ MeV and $K_0=380$ MeV can only partially describe the experimental results. In addition, we also study the directed and elliptic flows for the associated $\Lambda$, observations reveal the same conclusions as for kaons. These findings indicate that the momentum dependence of nuclear mean field plays a significant role in understanding nuclear matter properties in heavy-ion collisions at $\sqrt{s_{\rm NN}}=3$ GeV.

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arXiv2024

Kaon production in the HADES experiment in Au+Au collisions at $\sqrt{s_{\rm NN}}=2.4$ GeV

Within an isospin- and momentum-dependent transport model by including the kaon reaction channels, we study the kaon prodution in heavy-ion collisions (HICs) at SIS (Darmstadt Schwerionen Synchrotron, GSI) energies. Based on simulations of a centrality of 0-40% Au + Au collision at $\sqrt{s_{NN}}=2.4$ GeV, a typical reaction that has been carried out by the HADES Collaboration, we confirm that the medium modification of kaon masses plays a vital role in studying the kaon productions in HICs, and is also unavoidable for the successful interpretation of the HADES data on kaon rapidity distributions and transverse mass spectra. Moreover, it is shown that the directed flows of kaons are affected significantly by the kaon potential and slightly affected by the medium modification of kaon masses. Also, the rapidity-dependent inverse slope parameter $T_{B}$ of the kaon transverse mass spectra is shown to be affected considerably by both the kaon potential and medium modification of kaon masses. However, through checking the simulations of related reactions in FOPI and/or KaoS experiments, some of these regular effects do not seem to be obvious and appear to be the reaction system and/or beam energy dependent. Nevertheless, it can be confirmed that the medium modification of kaon masses is favored by observations from the inverse slope parameter $T_{B}$ and transverse mass spectra of kaons in both HADES Au + Au collisions at $\sqrt{s_{NN}}=2.4$ GeV and FOPI Ni + Ni collisions at 1.93\textit{A} GeV. Therefore, measurements of the inverse slope parameter $T_{B}$ of kaon transverse mass spectra and the kaon directed flows in HADES Au + Au collisions would be great benefit to detection of the kaon potential and the corresponding medium effects on kaon masses.

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