Nagoya University
Theoretical Elementary Particle Physics Laboratory

Date&Time Mon Jul 04 2022 (11:00 - 12:00)
Muneto Nitta
Affiliation Keio University
Title Stable Z-strings with topological polarization in two Higgs doublet model (with a review of topological solitons in this model)
Abstract After a review of topological solitons in the two Higgs doublet model, I will explain stable Z-strings based on ArXiv: 2111.13345 [hep-ph]: We find that a Z-string is stable in a wide range of parameter space of the two Higgs doublet model due to a split into a pair of two topological Z-strings with fractional Z fluxes. This configuration, a bound state of the two strings connected by a domain wall, is called a vortex molecule. Although the vortex molecule has no net topological charge, the locally induced topological charge density is polarized, namely distributed positively around one constituent string and negatively around the other constituent string, leading to the stability of the molecule. We numerically show that the vortex molecule is indeed a stable solution of the equation of motions in a much wider parameter space of the model than the usual axially symmetric Z-string in the Standard Model and the two Higgs doublet model, although it is not the case for experimental values of the parameters.