Magnetic field induced polarization difference between hyperons and anti-hyperons
Magnetic field induced polarization difference between hyperons and anti-hyperons
复制标题
超子与反超子之间的磁场诱发极化差异
DOI：
10.1016/j.physletb.2019.134929
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发表时间：
2019-05
影响因子：
4.4
通讯作者：
Jinfeng Liao
中科院分区：
文献类型：
--
作者：
Yu Guo;Shuzhe Shi;Shengqin Feng;Jinfeng Liao
最近的恒星测量表明，超子和反超子之间的全球自旋极化存在差异，特别是在碰撞束能量相对较低的情况下。造成这种差异的一个可能原因是介质中磁场的潜在存在。在这项研究中，我们考察了这种解释的现象学可行性。利用AMPT模型框架，我们量化了不同的磁场演化场景对大范围碰撞束能量中极化差大小的影响。我们发现，这种差异对磁场的寿命非常敏感。对于相同的寿命，计算的偏振差仅轻微地取决于其演化的详细形式。假设磁极化是增强反超子信号而抑制超子信号的机制，我们唯象地提取了所需磁场寿命的上限，以便解释实验数据。由此得到的寿命值大致符合与束流能量成反比的标度关系。文中还讨论了对其他与磁场有关的效应的可能影响。
Recent STAR measurements suggest a difference in the global spin polarization between hyperons and anti-hyperons, especially at relatively low collision beam energy. One possible cause of this difference is the potential presence of in-medium magnetic field. In this study, we investigate the phenomenological viability of this interpretation. Using the AMPT model framework, we quantify the influence of different magnetic field evolution scenarios on the size of the polarization difference in a wide span of collision beam energies. We find that such difference is very sensitive to the lifetime of the magnetic field. For the same lifetime, the computed polarization difference only mildly depends on the detailed form of its evolution. Assuming magnetic polarization as the mechanism to enhance anti-hyperon signal while suppress hyperon signal, we phenomenologically extract an upper limit on the needed magnetic field lifetime in order to account for the experimental data. The so-obtained lifetime values are in a quite plausible ballpark and follow approximately the scaling relation of being inversely proportional to the beam energy. Possible implications on other magnetic field related effects are also discussed.
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