Probing the $L_{\hat{I}}¼-L_{\ddot{I}}„$ gauge boson at electron colliders

Abstract

We investigate the minimal $U(1{)}_{L_{\hat{I}}¼-L_{\ddot{I}}„}$ model with extra heavy vector-like leptons or charged scalars. By studying the kinetic mixing between $U(1{)}_{L_{\hat{I}}¼-L_{\ddot{I}}„}$ gauge boson $Z^{\prime }$ and standard model photon, which is absent at tree level and will arise at one loop level due to $\hat{I}¼$, $\ddot{I}„$ and new heavy charged leptons or scalars, the interesting behavior is shown. It can provide possibility for visible signatures of new heavy particles. We propose to search for $Z^{\prime }$ at electron collider experiments, such as Belle II, BESIII and future Super Tau Charm Factory (STCF), using the monophoton final state. The parameter space of $Z^{\prime }$ is probed, and scanned by its gauge coupling constant $g_{Z^{\prime }}$ and mass $m_{Z^{\prime }}$. We find that electron colliders have sensitivity to the previously unexplored parameter space for $Z^{\prime }$ with MeV-GeV mass. Future STCF experiments with $\sqrt{s}=2-7$ GeV can exclude the anomalous muon magnetic moment favored area when $m_{Z^{\prime }}<5$ GeV with the luminosity of 30 ab${}^{-1}$. For $m_{Z^{\prime }}<2m_{\hat{I}}¼$, $g_{Z^{\prime }}$ can be down to $4.2\times 10^{-5}$ at 2 GeV STCF.

12 pages, 10 figures. Accepted for publication in Physical Review D