No net charge separation in hot QCD in a magnetic field
No net charge separation in hot QCD in a magnetic field
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DOI：
10.1103/physrevd.98.074009
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发表时间：
2018-07
影响因子：
5
通讯作者：
E. Ferrer;V. Incera
中科院分区：
文献类型：
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作者：
E. Ferrer;V. Incera
我们研究实现轴子电动力学在QCD中的背景磁场的存在下，在足够高的温度下发生的拓扑电荷跃迁，反映在存在的$\θ $-真空项的行动。我们表明，在这个系统中，麦克斯韦方程组包含两个相等的和相反的电流是成比例的轴子场的时间导数$\theta$。这些电流之一直接来自阿贝尔手征异常项的行动，可以解释为极化电流由于系统的CP-破缺对称性的磁电性。另一个电流是从规则蝌蚪图中得到的，可以理解为由介质手征不平衡和夸克在最低朗道能级的单自旋投影产生的。由于两个电流相互抵消，净电荷沿磁场沿着分离，这种现象被称为手征磁效应，至少在平衡状态下不会在高温QCD中发生，这与文献中的许多说法形成鲜明对比。我们讨论的相似性和差异外尔半金属在磁场中。
We study the realization of axion electrodynamics in QCD in the presence of a background magnetic field at temperatures high enough for the occurrence of topological charge transitions that are reflected in the presence of a $\theta$-vacuum term in the action. We show that in this system, the Maxwell equations contain two equal and opposite electric currents that are proportional to the time derivative of the axion field $\theta$. One of these currents comes directly from the Abelian chiral anomaly term in the action and can be interpreted as a polarization current due to the magnetoelectricity of the system with CP-broken symmetry. The other current is obtained from the regular tadpole diagrams and can be understood as produced by the medium chiral imbalance and the single spin projection of the quarks in the lowest Landau level. Since the two currents cancel out, the net electric charge separation along the magnetic field, a phenomenon known as the Chiral Magnetic Effect, does not take place in hight-T QCD at least in equilibrium, in sharp contrast with many claims in the literature. We discuss the similarities and differences with Weyl semimetals in a magnetic field.