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

Abstract

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 $G_{\mathrm{SM}}\equiv SU(3{)}_c\times SU(2{)}_L\times U(1{)}_Y$, 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 $H_{\mathrm{SM}}\equiv SU(3{)}_c\times U(1{)}_{\mathrm{em}}$ of $G_{\mathrm{SM}}$. 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. The Higgs-dilaton(radion) system considered in this work has a number of distinctive features that could be tested by the upcoming LHC running and at the ILC.

Comments: Minor corrections, including a few new figures, version appearing in Physics Letters B