Novel mechanism for electric quadrupole moment generation in relativistic heavy-ion collisions
Novel mechanism for electric quadrupole moment generation in relativistic heavy-ion collisions
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DOI：
10.1016/j.physletb.2019.04.002
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发表时间：
2019-01
影响因子：
4.4
通讯作者：
Xin-li Zhao;G. Ma;Yugang Ma
中科院分区：
文献类型：
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作者：
Xin-li Zhao;G. Ma;Yugang Ma
基于多相输运模型，给出了在RHIC能量s= 200 GeV下Au+ Au碰撞中电磁场（E和B）的空间分布和电磁异常E⋅B。在非中心碰撞中观察到E·B的偶极分布。我们发现，E⋅B偶极子与磁场B的耦合可以诱发电四极矩，而电四极矩通过最终相互作用进一步导致正电荷粒子与负电荷粒子之间的椭圆流差异。E·B密度的中心性依赖性与STAR合作测量的正、负介子椭圆流差的斜率参数r的变化趋势相似。因此，电四极矩产生的新机制可以在不形成手性电磁波的情况下，为观测到的电荷依赖的π介子椭圆流提供新的解释。
We present the spatial distributions of electromagnetic fields (E and B) and electromagnetic anomaly E⋅ B in Au+ Au collisions at the RHIC energy s= 200 GeV based on a multi-phase transport model. A dipolar distribution of E⋅ B is observed in non-central collisions. We find that the coupling of the E⋅ B dipole and magnetic field B can induce an electric quadrupole moment which can further lead to the difference in elliptic flows between positive charged particles and negative charged particles through final interactions. The centrality dependence of the density of E⋅ B is similar to the trend of the slope parameter r measured from the difference in elliptic flows between positive pions and negative pions by the STAR collaboration. Therefore, the novel mechanism for electric quadrupole moment generation can offer a new interpretation of the observed charge-dependent elliptic flow of pions, but without the formation of chiral magnetic wave.