Non-Abelian strings and domain walls in two Higgs doublet models

Understand

Contrary to the standard model that does not admit topologically nontrivial solitons, two Higgs doublet models admit topologically stable vortex strings and domain walls.

• We numerically confirm the existence of a topological $Z$-string confining fractional $Z$-flux inside.
• We show that topological strings at $\sin\theta_W = 0$ limit reduce to non-Abelian strings which possess non-Abelian moduli $S^2$ associated with spontaneous breakdown of the $SU(2)$ custodial symmetry.
• We numerically solve the equations of motion for various parameter choices.