A Tale of Two Twin Higgses: Addressing Little Hierarchy in Natural 2HDM Framework

Understand

In original twin Higgs model, vacuum misalignment between electroweak and new physics scales is realized by adding explicit $\mathbb{Z}_2$ breaking term.

• Introducing additional twin Higgs could accommodate spontaneous $\mathbb{Z}_2$ breaking, which explains the origin of this misalignment.
• We introduce a class of two twin Higgs doublet models with most general scalar potential, and discuss general conditions which trigger electroweak and $\mathbb{Z}_2$ symmetry breaking.
• Various scenarios on realising the vacuum misalignment are systematically discussed in a natural two Higgs double model framework: explicit $\mathbb{Z}_2$ breaking, radiative $\mathbb{Z}_2$ breaking, tadpole-induced $\mathbb{Z}_2$ breaking, and quartic-induced $\mathbb{Z}_2$ breaking.