高重子密度下核-核碰撞中直接${\rm{K}}^{*}$产生及强子介质效应的唯象学研究

中文摘要 AI 辅助

短寿命强子共振态是高重子密度重离子碰撞中晚期强子介质的灵敏探针。利用AMPT-HC模型，我们研究了在$\u221A{s_{\rm{NN}}} = 3$ GeV的Au+Au碰撞中${\rm{K}}^{*}(892)$的产生及其强子介质效应，该能量区域具有高重子密度。我们引入了一种唯象的直接产生机制，通过将${\rm{NN}} \to {\rm{NYK}}$和${\rm{MN}} \to {\rm{YK}}$通道中产生的部分末态kaon替换为${\rm{K}}^{*}$共振态，替换比例由参数$\alpha$控制，同时保持四动量守恒。直接${\rm{K}}^{*}$在约6 fm/$c$时早期产生，其产生时间几乎不依赖于中心度，而通过${\rm{K}}+\pi\to{\rm{K}}^{*}$的共振融合则发生较晚，平均产生时间从中心碰撞的约8 fm/$c$增加到10 fm/$c$。因此，直接${\rm{K}}^{*}$介子遭受更强的子代粒子再散射，导致重建效率在中心碰撞中显著降低，而${\rm{K}}^{*}$存活率仍接近1。子代粒子的弹性散射也会使不变质量偏离共振峰，贡献类似背景的成分。${\rm{K}}^{*}/{\rm{K}}$的中心度依赖性反映了直接产生与共振融合之间的竞争，并对$\alpha$敏感。在3 GeV能量下，适度的直接产生贡献可能导致${\rm{K}}^{*}/{\rm{K}}$比值在中心碰撞中增大，为未来测量提供了可检验的预言。

英文摘要

Short-lived hadron resonances serve as sensitive probes of the late-stage hadronic medium in heavy-ion collisions. Using the AMPT-HC model, we study ${\rm{K}}^{*}(892)$ production and its hadronic medium effects in Au+Au collisions at $\sqrt{s_{\rm{NN}}} = 3$ GeV, a region of high baryon density. We introduce a phenomenological direct-production mechanism for ${\rm K}^{*}$ by replacing a fraction of the final-state kaons produced in the ${\rm NN} \to {\rm NYK}$ and ${\rm MN} \to {\rm YK}$ channels with ${\rm K}^{*}$ resonances, with the substitution fraction controlled by a parameter $α$ while conserving four-momentum. The direct ${\rm K}^{*}$ is produced early, at about 6 fm/$c$, with little centrality dependence, whereas resonance fusion via ${\rm K}+π\to{\rm K}^{*}$ occurs later, with the mean production time increasing from about 8 to 10 fm/$c$ toward central collisions. Consequently, direct ${\rm K}^{*}$ mesons suffer stronger daughter rescattering, leading to a pronounced decrease in reconstruction efficiency toward central collisions, while the ${\rm K}^{*}$ survival rate remains close to unity. Elastic scattering of the daughters also shifts the invariant mass away from the resonance peak, contributing to the background-like component. The ${\rm K}^{*}/{\rm K}$ centrality dependence reflects the competition between direct production and resonance fusion and is sensitive to $α$. At 3 GeV, a moderate direct-production contribution may result in an increasing ${\rm K}^{*}/{\rm K}$ ratio toward central collisions, providing a testable prediction for future measurements.

发表机构

• Central China Normal University（华中师范大学）
• University of Chinese Academy of Sciences（中国科学院大学）
• Chinese Academy of Sciences（中国科学院）

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