Doubly-charged scalar in rare decays of $B_c$ meson

In this paper, we study the lepton number violation processes of $B_c$ meson induced by possible doubly-charged scalars. Both the three-body decay channels and the four-body decay channels are considered. For the former, $Br\times {\left(\frac{s_{\mathrm{\Delta }}{h}_{ij}}{M_{\mathrm{\Delta }}^2}\right)}^{-2}$ is of the order of ${10}^{-7}\sim {10}^{-9}$, and for the later channels, $Br\times {\left(\frac{s_{\mathrm{\Delta }}{h}_{ij}}{M_{\mathrm{\Delta }}^2}\right)}^{-2}$ is of the order of ${10}^{-12}\sim {10}^{-20}$, where $s_{\mathrm{\Delta }}$, $h_{ij}$, $M_{\mathrm{\Delta }}$ are the constants related to the doubly-charged boson.