Charged Higgs boson effects in the production and decay of a heavy Majorana neutrino at the CERN LHC

We consider a new interaction between a heavy Majorana neutrino ($N$) and a charged Higgs boson ($H^{\pm }$), and show that it can have drastic implications on lepton-number-violating (LNV) signal of same-sign dileptons at the CERN LHC. The LNV signal of heavy Majorana neutrinos previously considered at the LHC, $pp\to {\ell }^{+}N\to {\ell }^{+}{\ell }^{+}{W}^{-}$, may be overwhelmed by $pp\to {\ell }^{+}N\to {\ell }^{+}{\ell }^{+}{H}^{-}$. With the subsequent decays $H^{-}\to \overline{t}b$ or $H^{-}\to W^{-}{H}^0$, the heavy Majorana neutrino production leads to the spectacular events of ${\ell }^{+}{\ell }^{+}b\overline{b}+2$ jets. We also explore the case $m_N<m_{H^{+}}$, where the decay $H^{+}\to {\ell }^{+}N$ can become the dominant $N$-production mechanism at the LHC. In particular, we show that the process $gb\to t{H}^{-}$ followed by $t\to b{W}^{+}$ and $H^{-}\to {\ell }^{-}N\to {\ell }^{-}{\ell }^{-}{W}^{+}$ could lead to another type of spectacular events of ${\ell }^{-}{\ell }^{-}b+4$ jets.