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.
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Acknowledgments
We would like to thank Luis Hellmich, Thomas Konstandin, Wilfried Buchmüller, Raymond R. Volkas and the members of the DESY 2HDM working group for useful discussions and comments. This work is funded by the Deutsche Forschungsgemeinschaft (DFG) through Germany’s Excellence Strategy — EXC 2121 “Quantum Universe” — 390833306. Figures presented in this work were generated using MatPlotLib [47] and NumPy [48].
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Sassi, M.Y., Moortgat-Pick, G. Domain walls in the Two-Higgs-Doublet Model and their charge and CP-violating interactions with Standard Model fermions. J. High Energ. Phys. 2024, 101 (2024). https://doi.org/10.1007/JHEP04(2024)101
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DOI: https://doi.org/10.1007/JHEP04(2024)101