arXiv 1106.40302011-06-20hep-th

芳香化合物AdS/CFT的手性磁效应

A Chiral Magnetic Effect from AdS/CFT with Flavor

Carlos Hoyos, Tatsuma Nishioka, Andy O'Bannon

备注：: 54 pages, 18 eps files in 6 figures
DOI：: 10.1007/JHEP10(2011)084

摘要：

对于（3+1）维费米子，轴向净电荷和外部磁场可以导致平行于磁场的电流。这就是手性磁效应。本文利用规范引力对偶性研究了大Nc强耦合N=4超对称SU（Nc）Yang-Mills理论中的手征磁效应，该理论耦合到SU（Nc）的Nc表示中的Nf << Nc个N=2超多重态，即味场.具体来说，我们引入一个外部磁场和一个随时间变化的相位的质量的味场，这是相当于一个轴向化学势的味费米子，我们计算全息所得的手征磁流。对于无质量的味道，我们发现，目前采取的值所确定的轴向异常。对于有质量的味道，电流只出现在赝标介子凝聚体的存在下，并且具有比无质量味道更小的值，对于足够大的质量或磁场，电流降为零。在我们的系统中的轴对称性是R对称性的一部分，我们研究的状态涉及轴向电荷从耦合到味道的外部源到伴随扇区的净流动。我们用场论和全息术计算了轴向电荷和能量随时间的变化率，两者完全一致。与以前的手征磁效应全息模型相比，在我们的系统中，矢量电流是守恒的，并且没有任何特殊的反项。

英文摘要：

For (3+1)-dimensional fermions, a net axial charge and external magnetic field can lead to a current parallel to the magnetic field. This is the chiral magnetic effect. We use gauge-gravity duality to study the chiral magnetic effect in large-Nc, strongly-coupled N=4 supersymmetric SU(Nc) Yang-Mills theory coupled to a number Nf << Nc of N=2 hypermultiplets in the Nc representation of SU(Nc), i.e. flavor fields. Specifically, we introduce an external magnetic field and a time-dependent phase for the mass of the flavor fields, which is equivalent to an axial chemical potential for the flavor fermions, and we compute holographically the resulting chiral magnetic current. For massless flavors we find that the current takes the value determined by the axial anomaly. For massive flavors the current appears only in the presence of a condensate of pseudo-scalar mesons, and has a smaller value than for massless flavors, dropping to zero for sufficiently large mass or magnetic field. The axial symmetry in our system is part of the R-symmetry, and the states we study involve a net flow of axial charge to the adjoint sector from an external source coupled to the flavors. We compute the time rate of change of axial charge and of energy both in field theory and from holography, with perfect agreement. In contrast to previous holographic models of the chiral magnetic effect, in our system the vector current is conserved and gauge-invariant without any special counterterms.

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摘要：

英文摘要：

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