Constraining the Active-to-Heavy-Neutrino transitional magnetic moments associated with the $Z'$ interactions at FASER$\nu$

Abstract

We investigate the effects of the transitional magnetic dipole moment of the active-to-heavy-neutrino associated with a new neutral gauge boson $Z'$ on neutrino-nucleon scattering at the ForwArd Search ExpeRiment-$\nu$ (FASER$\nu$). We consider the neutral-current neutrino-nucleon scattering ($\nu A\rightarrow N A$) as the production mechanism of the heavy neutrino $N$ at FASER$\nu$ and estimate the sensitivity reach on the magnetic moment coupling $\mu_{\nu_\alpha}$ for a range of heavy neutrino mass ($1\,{\rm GeV} < M_{N} < 70 {\rm GeV}$). In this study, we consider three benchmark models, in which the heavy neutrino is coupled to $L_e$, $L_\mu$ or $L_\tau$ doublet, respectively.