Higgs-dilaton(radion) system confronting the LHC Higgs data

Understand

We consider the Higgs-dilaton(radion) system using the trace of energy-momentum tensor ($T_{~\mu}^\mu$) with the full Standard Model (SM) gauge symmetry $G_{\rm SM} \equiv SU(3)_c \times SU(2)_L \times U(1)_Y$, and find out that the resulting phenomenology for the Higgs-dilaton(radion) system is distinctly different from the earlier studies based on the $T_{~\mu}^\mu$ with the unbroken subgroup $H_{\rm SM} \equiv SU(3)_c \times U(1)_{\rm em}$ of $G_{\rm SM}$.

• After electroweak symmetry breaking (EWSB), the SM Higgs boson and dilaton(radion) will mix with each other, and there appear two Higgs-like scalar bosons and the Higgs-dilaton mixing changes the scalar phenomenology in interesting ways.
• The signal strengths for the $gg$-initiated channels could be modified significantly compared with the SM predictions due to the QCD scale anomaly and the Higgs-dilaton(radion) mixing, whereas anomaly contributions are almost negligible for other channels.
• We also discuss the self-couplings and the signal strengths of the $126$ GeV scalar boson in various channels and possible constraints from the extra light/heavy scalar boson.