Speaker
Description
We consider a classically conformal $U(1)$ extension of the Standard Model (SM).
The $U(1)$ symmetry is radiatively broken by the Coleman-Weinberg mechanism, after which the $U(1)$ Higgs field $\phi$ drives electroweak symmetry breaking through a mixed quartic coupling with the SM Higgs doublet with coupling constant $\lambda_{mix}$.
We calculate the Higgs triple couplings in this system and find a suppression of the coupling $g_{h_{1} h_{2} h_{2}}$ when compared to the naively expected value $g_{h_{1} h_{2} h_{2}} \sim \lambda_{mix} v_{h}$ ($v_{h} = 246$ GeV), likely due to the unique nature of the classically conformal potential.
We consider experimental signals for such conformal structure via the anomalous Higgs boson decay $h \rightarrow \phi \phi$ and anomalous SM Higgs boson couplings.
Such specific conformal structure would allow for a sizeable anomalous SM Higgs boson coupling alongside a heavily suppressed $h \rightarrow \phi \phi$ decay mode, which can be tested by future $e^{+}e^{-}$ linear colliders.
