125 GeV Technidilaton at the LHC

Abstract: The technidilaton (TD) is a composite scalar predicted in walking technicolor (WTC), arising as a pseudo Nambu-Goldstone boson associated with the spontaneous breaking of the approximate scale invariance. Due to the Nambu-Goldstone boson's nature, the TD can be as light as the LHC boson that has been discovered at around 125 GeV. We discuss the size of the TD mass and the coupling properties relevant to the LHC study. It turns out that the TD couplings to the standard model (SM) particles take the same form as those of the SM Higgs boson, except the essentially distinguishable two ingredients: i) the overall coupling strengths set by the decay constant related to the spontaneous breaking of the scale invariance, which is in general not equal to the electroweak scale; ii) the couplings to photons and gluons which can include extra contributions from technifermion loops and hence can be enhanced compared to the SM Higgs case. To be concrete, we take the one-family technicolor model to explore the TD LHC phenomenology at 125 GeV. It is shown that the TD gives the signal consistent with the currently reported LHC data, notably can explain the excess in the diphoton channel, due to the extra contributions to digluon and diphoton couplings coming from the one-family technifermion loops.