Formation of a chiral soliton lattice
Formation of a chiral soliton lattice
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DOI：
10.1103/physrevd.106.096022
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发表时间：
2022-07
影响因子：
5
通讯作者：
Tetsutaro Higaki;K. Kamada;K. Nishimura
中科院分区：
文献类型：
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作者：
Tetsutaro Higaki;K. Kamada;K. Nishimura
手征孤子晶格(CSL)是一种由等间隔平行排列的磁畴壁组成的晶格结构，由于手征反常产生的拓扑项，它在背景磁场和有限(重子)化学势的存在下是能量稳定的。基于Nambu-Goto型有效理论，我们从真空态出发研究了CSL的形成，将CSL描述为一层被涡旋或弦环包围的磁区-壁圆盘。我们发现，当磁场足够强时，磁化壁会通过量子隧道成核。我们评估了它的成核率，并确定了成核率不再被指数抑制的临界磁场强度。我们将这一分析应用于双味QCD中的中性介子以及外加磁场作用下具有有限(重子)化学势的类轴子粒子(AlP)。在前一种情况下，即使CSL态比真空态能量更稳定，并且在足够强的磁场下成核速率变得更大，但它也不可能足够大，从而不会指数地抑制和促进磁畴壁的成核，而不会受到带电介子涨落的速子不稳定性的影响。在后一种情况下，我们确认阿尔卑斯山的有效相互作用一般包括CSL态获得能量有利所需的拓扑项。我们发现，当系统的磁场强度和化学势略大于轴子衰变常数的范围时，ALP CSL的形成是促进的。
The Chiral Soliton Lattice (CSL) is a lattice structure composed of domain walls aligned in parallel at equal intervals, which is energetically stable in the presence of a background magnetic field and a finite (baryon) chemical potential due to the topological term originated from the chiral anomaly. We study its formation from the vacuum state, with describing the CSL as a layer of domain-wall disks surrounded by the vortex or string loop, based on the Nambu-Goto-type effective theory. We show that the domain wall nucleates via quantum tunneling when the magnetic field is strong enough. We evaluate its nucleation rate and determine the critical magnetic field strength with which the nucleation rate is no longer exponentially suppressed. We apply this analysis to the neutral pion in the two-flavor QCD as well as the axion-like particles (ALPs) with a finite (baryon) chemical potential under an external magnetic field. In the former case, even though the CSL state is more energetically stable than the vacuum state and the nucleation rate becomes larger for sufficiently strong magnetic field, it cannot be large enough so that the nucleation of the domain walls is not exponentially suppressed and promoted, without suffering from the tachyonic instability of the charged pion fluctuations. In the latter case, we confirm that the effective interaction of the ALPs generically includes the topological term required for the CSL state to be energetically favored. We show that the ALP CSL formation is promoted if the magnetic field strength and the chemical potential of the system is slightly larger than the scale of the axion decay constant.