Doubly-charged scalar in four-body decays of neutral flavored mesons

Abstract

In this paper, we study the four-body decay processes of neutral flavored mesons, including ${\bar{K}}^0$, $D^0$, ${\bar{B}}^0$, and ${\bar{B}}_s^0$. These processes, which induced by a hypothetical doubly-charged scalar particle, violate the lepton number. The quantity $Br\times {\left(\frac{s_{\Delta }{h}_{ij}}{m_{\Delta }^2}\right)}^{-2}$ of different channels are calculated, where $s_{\Delta }$, $h_{ij}$, and $M_{\Delta }$ are parameters related to the doubly-charged scalar. For ${\bar{K}}^0\to h_1^{+}{h}_2^{+}{l}_1^{-}{l}_2^{-}$, $D^0\to h_1^{-}{h}_2^{-}{l}_1^{+}{l}_2^{+}$, and ${\bar{B}}_{d,s}^0\to h_1^{+}{h}_2^{+}{l}_1^{-}{l}_2^{-}$, it is of the order of $10^{-13}\sim 10^{-11}$ $\mathrm{Ge}{\mathrm{V}}^4$, $10^{-17}\sim 10^{-10}$ $\mathrm{Ge}{\mathrm{V}}^4$, and $10^{-17}\sim 10^{-10}$ $\mathrm{Ge}{\mathrm{V}}^4$, respectively. Based on the experimental results for the $D^0\to h_1^{-}{h}_2^{-}{l}_1^{+}{l}_2^{+}$ channels, we also set the upper limit for $\frac{s_{\Delta }{h}_{ij}}{M_{\Delta }^2}$.

15 pages, 2 figures