Abstract
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.
Highlights
In cosmology, they were expected to contribute to the anisotropy of the cosmic microwave background [1, 5, 6] and galaxy structure formation [1, 7, 8]
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
We numerically show that the vortex molecule is 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, it is not the case for experimental values of the parameters
Summary
We introduce two SU(2) doublets of Higgs scalar fields, Φ1 and Φ2, both with the hypercharge Y = 1. Dμ represents the covariant derivative acting on the Higgs fields, and the index i runs i = 1, 2. The most generic quartic potential V (Φ1, Φ2) for the two Higgs doublets is given by. We rewrite the Higgs fields in a two-by-two matrix form [80], H, defined by. The matrix scalar field H transforms under the electroweak SU(2)W × U(1)Y symmetry as i i. The VEV of H is expressed by a diagonal matrix H = diag(v1, v2), and the Higgs potential can be rewritten by using H as follows:. The parameter sets in the Higgs potential in eqs.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
