Inverse magnetic catalysis and the Polyakov loop
Inverse magnetic catalysis and the Polyakov loop
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DOI：
10.1007/jhep04(2013)112
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发表时间：
2013-03
影响因子：
5.4
通讯作者：
F. Bruckmann;G. Endrődi;T. Kovács
中科院分区：
文献类型：
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作者：
F. Bruckmann;G. Endrődi;T. Kovács
我们研究外部磁场如何影响 QCD 夸克凝聚体的物理机制。确定了两种相互竞争的机制，两者都依赖于磁场和低夸克模式之间的相互作用。虽然与价夸克的耦合增强了凝聚态，但与海夸克的相互作用却在过渡区抑制了凝聚态。后者的“海洋效应”通过对波利亚科夫环进行排序来起作用，从而减少小狄拉克本征模和凝聚体的数量。它在转变温度附近最有效，此时波利亚科夫环有效电势是平坦的，并且通过磁场对其进行小的修正可以产生显着的效果。在临界温度附近，海抑制压倒了化合价增强，导致凝析油的净抑制，称为逆磁催化。我们通过晶格模拟支持这一物理图景，包括作为温度和磁场函数的波利亚科夫环的连续外推结果。我们认为，考虑到波利亚科夫环的增加及其与低位模的相互作用对于获得完整的物理图像至关重要，并且应该将其纳入描述过渡区磁场中 QCD 的有效模型中。
We study the physical mechanism of how an external magnetic field influences the QCD quark condensate. Two competing mechanisms are identified, both relying on the interaction between the magnetic field and the low quark modes. While the coupling to valence quarks enhances the condensate, the interaction with sea quarks suppresses it in the transition region. The latter “sea effect” acts by ordering the Polyakov loop and, thereby, reduces the number of small Dirac eigenmodes and the condensate. It is most effective around the transition temperature, where the Polyakov loop effective potential is flat and a small correction to it by the magnetic field can have a significant effect. Around the critical temperature, the sea suppression overwhelms the valence enhancement, resulting in a net suppression of the condensate, named inverse magnetic catalysis. We support this physical picture by lattice simulations including continuum extrapolated results on the Polyakov loop as a function of temperature and magnetic field. We argue that taking into account the increase in the Polyakov loop and its interaction with the low-lying modes is essential to obtain the full physical picture, and should be incorporated in effective models for the description of QCD in magnetic fields in the transition region.