利用组合机制研究Λ与反Λ极化劈裂效应
Investigate the $Λ$ and $\barΛ$ polarization splitting effect with combined mechanisms
AI总结：
本文在PICR流体力学模型基础上组合介子场、冻出时空和QGP磁场三种机制，解释STAR实验中Λ与反Λ极化劈裂，发现介子场机制主导，组合后劈裂平均值提升至4.5%，更接近实验值5.8%。
摘要：
STAR合作组在Au+Au 7.7 GeV碰撞中测得的Λ与反Λ极化显著劈裂现象幅度很大，任何单一机制都难以令人满意地描述，因此我们在PICR流体力学模型基础上重新审视并将三种不同机制组合起来，以解释实验数据。这三种机制，即介子场机制、冻出时空机制和QGP磁场机制，分别作用于高能碰撞的不同阶段，因而彼此并不矛盾。我们发现介子场机制占主导地位，而QGP磁场机制相当微弱，冻出时间效应受到冻出时间差很小的限制，从而形成ΔP_J ≫ ΔP_t ≫ ΔP_m的层级关系。此外，不同机制的组合可以将极化劈裂的平均值从约3%-4%提升至4.5%，更接近实验测得的平均值5.8%。
英文摘要：
The significant splitting of $Λ$ and $\barΛ$ polarization measured in STAR's Au+Au 7.7GeV collisions seems to be huge and unable to be described satisfactorily by any single mechanism, thus we revisit and combine there different mechanisms together on the basis of our PICR hydrodynamic model, to explain the experimental data. The three mechanisms, i.e. the meson field mechanism, the freeze-out space-time mechanism, and the QGP's magnetic field mechanism, lie on different stage of high energy collisions, and thus are not contradicted with each other. We find that the meson field mechanism is dominat, while the QGP's magnetic field mechanism is rather trivial, and freeze-out time effect is restricted by the small FZ time difference, leading to a hierarchy of $ΔP_J \gg ΔP_t \gg ΔP_m$. Besides, the combination of different mechanisms could promote the mean value of polarization splitting from about 3\%-4\% to 4.5\%, which is more close to the experimental measured mean value of 5.8\%.
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