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

We study a model with $U(1)_{L_��- L_��}$ gauge symmetry and discuss collider searches for a scalar boson, which breaks $U(1)_{L_��- L_��}$ 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, $��$ with $\mathcal{O}(100)$ GeV mass appears associated with the symmetry breaking. We investigate experimental constraints on $U(1)_{L_��- L_��}$ gauge coupling, kinetic mixing, and mixing between the SM Higgs and $��$. Then collider search is discussed considering $��$ production followed by decay process $��\to Z' Z'$ at the large hadron collider and the international linear collider. We also estimate discovery significance at the linear collider taking into account relevant kinematical cut effects.

28 pages, 9 figures, 5 tables: published version