近日，德国汉堡大学的Mohamed Younes Sassi及其研究团队取得一项新进展。经过不懈努力，他们对双希格斯-双重态模型中的畴壁及其与标准模型费米子的电荷和CP违反相互作用进行了研究。相关研究成果已于2024年4月18日在国际知名学术期刊《高能物理杂志》上发表。
因此，该研究团队最终得到了几类畴壁解，它们各自具备不同的壁内特性，如电荷和/或CP破坏的真空状态。研究人员深入探讨了这些不同类型的畴壁解的性质，以及SM费米子与这些拓扑缺陷之间的相互作用。这些拓扑缺陷导致了各种奇特的物理现象，例如顶夸克可能从畴壁上传输或反射为底夸克。
据悉，离散对称性在粒子物理标准模型(SM)的几种扩展中起着重要作用。例如，为了避免味变化的中性电流，在双希格斯-双重态模型(2HDM)上施加了一个离散的Z2对称。在宇宙早期的电弱对称性破缺过程中，Z2对称性会自发破缺，进而在真空与离散对称性相关的区域间形成畴壁（DW）。由于离散对称和电弱对称的同时自发破缺，真空流形由两个互不连接的3球组成。这种非平凡且不连贯的真空流形导致相邻区域间的真空选择多样化，这与仅离散对称自发破缺且真空流形由若干不连贯点构成的模型截然不同。
附：英文原文
Title: Domain walls in the Two-Higgs-Doublet Model and their charge and CP-violating interactions with Standard Model fermions
Author: Sassi, Mohamed Younes, Moortgat-Pick, Gudrid
Issue&Volume: 2024-04-18
Abstract: Discrete symmetries play an important role in several extensions of the Standard Model (SM) of particle physics. For instance, in order to avoid flavor changing neutral currents, a discrete Z2 symmetry is imposed on the Two-Higgs-Doublet Model (2HDM). This can lead to the formation of domain walls (DW) as the Z2 symmetry gets spontaneously broken during electroweak symmetry breaking in the early universe and domain walls form between regions whose vacua are related by the discrete symmetry. Due to this simultaneous spontaneous breaking of both the discrete symmetry and the electroweak symmetry, the vacuum manifold consists of two disconnected 3-spheres. Such a non-trivial disconnected vacuum manifold leads to several choices for the vacua at two adjacent regions, in contrast to models where only the discrete symmetry gets spontaneously broken and the vacuum manifold consists of several disconnected points. Due to this, we end up with several classes of DW solutions having different properties localized inside the wall, such as electric charge and/or CP violating vacua. We discuss the properties of these different classes of DW solutions as well as the interaction of SM fermions with such topological defects leading to different exotic phenomena such as, for example, the top quark being transmitted or reflected off the wall as a bottom quark.
DOI: 10.1007/JHEP04(2024)101
Source: https://link.springer.com/article/10.1007/JHEP04(2024)101