# Search for heavy Majorana neutrino in lepton number violating decays of $D\to K\pi {e}^{+}{e}^{+}$

07 June 2019

Abstract: Using a data sample with an integrated luminosity of $2.93\text{}\text{}{\mathrm{fb}}^{-1}$ taken at the center-of-mass energy of 3.773 GeV, we search for the Majorana neutrino (${\nu }_{m}$) in the lepton number violating decays $D\to K\pi {e}^{+}{e}^{+}$. No significant signal is observed, and the upper limits on the branching fraction at the 90% confidence level are set to be $B\left({D}^{0}\to {K}^{-}{\pi }^{-}{e}^{+}{e}^{+}\right)<2.8×{10}^{-6}$, $B\left({D}^{+}\to {K}_{S}^{0}{\pi }^{-}{e}^{+}{e}^{+}\right)<3.3×{10}^{-6}$ and $B\left({D}^{+}\to {K}^{-}{\pi }^{0}{e}^{+}{e}^{+}\right)<\phantom{\rule{0ex}{0ex}}8.5×{10}^{-6}$. The Majorana neutrino is searched for with different mass assumptions ranging from 0.25 to $1.0\text{}\text{}\mathrm{GeV}/{c}^{2}$ in the decays ${D}^{0}\to {K}^{-}{e}^{+}{\nu }_{m},{\nu }_{m}\to {\pi }^{-}{e}^{+}$ and ${D}^{+}\to {K}_{S}^{0}{e}^{+}{\nu }_{m},{\nu }_{m}\to {\pi }^{-}{e}^{+}$, and the upper limits on the branching fraction at the 90% confidence level are at the level of ${10}^{-7}\sim {10}^{-6}$, depending on the mass of the Majorana neutrino. The constraints on the mixing matrix element $|{V}_{e{\nu }_{m}}{|}^{2}$ are also evaluated.

Published in: Physical Review D 99 (2019)