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

Abstract

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 $Z^{\prime }$ gauge boson. In this model, the new gauge boson, $Z^{\prime }$, 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, $\varphi$ 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 $\varphi$. Then collider search is discussed considering $\varphi$ production followed by decay process $\varphi \to Z^{\prime }{Z}^{\prime }$ 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.

Comments: 28 pages, 9 figures, 5 tables: published version