We study the dynamics of the Nambu monopole in two Higgs doublet models, which is a magnetic monopole attached by two topological $Z$ strings ($Z$ flux tubes) from two opposite sides. The monopole is a topologically stable solution of the equation of motions when the Higgs potential has global $U(1)$ and $\mathbb{Z}_2$ symmetries. In this paper, we consider more general cases without the $\mathbb{Z}_2$ symmetry, and find that it is no longer a static solution but moves along the $Z$ string being pulled by the heavier string. After analytically constructing an asymptotic form of the monopole, we confirm such a motion using the numerical relaxation method. In addition, we analyze the real time dynamics of the monopole based on a point-like approximation. Consequently, if there were long string networks with the monopoles in the early universe, the monopole accelerates nearly to the speed of light emitting electromagnetic radiations as a synchrotron accelerator, and collides to an anti-monopole on the string. This collision event, which we call the cosmological monopole collider, can produce much heavier particles than those we can see today, e.g., at the Large Hadron Collider.

中文翻译：

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两个希格斯双峰模型中南部单极子的动力学。宇宙单极对撞机

我们在两个希格斯双峰模型中研究了南部单极子的动力学，这是一个磁单极子，由两个相对侧的两个拓扑 $Z$ 弦（$Z$ 通量管）连接。当希格斯势具有全局 $U(1)$ 和 $\mathbb{Z}_2$ 对称性时，单极子是运动方程的拓扑稳定解。在本文中，我们考虑没有 $\mathbb{Z}_2$ 对称性的更一般情况，发现它不再是一个静态解，而是沿着被较重的弦拉动的 $Z$ 弦移动。在分析构建单极子的渐近形式后，我们使用数值松弛方法确认了这种运动。此外，我们基于点状近似分析了单极子的实时动态。因此，如果在早期宇宙中存在具有单极子的长弦网络，单极子作为同步加速器加速到接近发射电磁辐射的速度，并与弦上的反单极子相撞。这种碰撞事件，我们称之为宇宙学单极对撞机，可以产生比我们今天看到的更重的粒子，例如，在大型强子对撞机上。