Searching for scalar boson decaying into light $Z'$ boson at collider experiments in $U(1)_{L_\mu-L_\tau}$ model

Understand

We study a model with $U(1)_{L_\mu - L_\tau}$ gauge symmetry and discuss collider searches for a scalar boson, which breaks $U(1)_{L_\mu - L_\tau}$ symmetry spontaneously, decaying into light $Z'$ gauge boson.

• In this model, the new gauge boson, $Z'$, with a mass lighter than $\mathcal{O}(100)$ MeV, plays a role in explaining the anomalous magnetic moment of muon via one-loop contribution.
• For the gauge boson to have such a low mass, the scalar boson, $\phi$ with $\mathcal{O}(100)$ GeV mass appears associated with the symmetry breaking.
• We investigate experimental constraints on $U(1)_{L_\mu - L_\tau}$ gauge coupling, kinetic mixing, and mixing between the SM Higgs and $\phi$.