Three-lepton signals of sterile neutrinos of the expanded lepton sector

The gauge model $SU(2)_L \times U(1)$ with extension of the lepton sector by right sterile Majorana neutrinos is considered. A block diagonalization of the total mass matrix $6 \times 6$ of light (active) and sterile neutrinos is performed for the general form of the mixing matrix in the sterile neutrino sector. Production rates and distributions for transverse momentum and rapidity for processes $pp \rightarrow Nl^{\pm}$ and $pp \rightarrow N\nu$ were studied including gluon fusion $gg \rightarrow h^{*}/Z^{*} \rightarrow N\nu$ at $\sqrt{s} = 13$ TeV LHC energy.