论文标题
带有增强对称性的Abelian-Higgs模型中的宇宙弦 - 与Axion域壁问题的影响 -
Cosmic String in Abelian-Higgs Model with Enhanced Symmetry -- Implication to the Axion Domain-Wall Problem --
论文作者
论文摘要
在以前的工作中，我们在Abelian-Higgs模型中找到了新型的宇宙弦乐解决方案，并具有增强的$ U（1）$全局对称性。我们将这些解决方案称为补偿/未补偿的字符串。补偿的弦类似于Abrikosov-Nielsen-Oersen（ANO）弦中的常规宇宙弦，只有可能的NAMBU-GOLDSTONE（NG）玻色子风。另一方面，在无偿的弦周围，物理NG玻色子也有风，其中物理NG玻色子与增强的对称性的自发断裂有关。我们先前在2+1维时段中的模拟证实，在对称性断裂的相变时，补偿/未补偿的字符串均形成。当将模型应用于轴突模型时，物理NG玻色子周围的物理NG玻色子的非平凡绕组可能会导致所谓的轴域壁问题。在本文中，我们在3+1维时段进行了模拟，以讨论未补偿字符串的命运。我们观察到，与先前的仿真相比，在3+1维模拟中，字符串网络的演变非常复杂。尽管存在这种并发症，但我们发现可能在晚期可能会高度抑制的无偿字符串数量。我们的观察结果表明，目前的设置可以应用于轴突模型，而不会遇到轴突壁壁问题。
In our previous work, we found new types of the cosmic string solutions in the Abelian-Higgs model with an enhanced $U(1)$ global symmetry. We dubbed those solutions as the compensated/uncompensated strings. The compensated string is similar to the conventional cosmic string in the Abrikosov-Nielsen-Olesen (ANO) string, around which only the would-be Nambu-Goldstone (NG) boson winds. Around the uncompensated string, on the other hand, the physical NG boson also winds, where the physical NG boson is associated with the spontaneous breaking of the enhanced symmetry. Our previous simulation in the 2+1 dimensional spacetime confirmed that both the compensated/uncompensated strings are formed at the phase transition of the symmetry breaking. Non-trivial winding of the physical NG boson around the strings potentially causes the so-called axion domain-wall problem when the model is applied to the axion model. In this paper, we perform simulation in the 3+1 dimensional spacetime to discuss the fate of the uncompensated strings. We observe that the evolution of the string-network is highly complicated in the 3+1 dimensional simulation compared with that seen in the previous simulation. Despite such complications, we find that the number of the uncompensated strings which could cause can be highly suppressed at late times. Our observation suggests that the present setup can be applied to the axion model without suffering from the axion domain-wall problem.
