Rare t-quark decays $t \to c l_j^{+} l_k^{-}$, $t \to c \tilde{\nu_j}   \nu_k$ in the minimal four color symmetry model
  The rare t-quark decays $t \to c l_j^{+} l_k^{-}$, $t \to c \tilde{\nu_j} \nu_k$ via the scalar leptoquark doublets are investigated in the minimal four color symmetry model with the Higgs mechanism of the quark-lepton mass splitting. The partial widths of these decays are calculated and the total width of the charged lepton mode $ \Gamma(t \to c {l^{+}}' l^{-})= \sum_{j,k} \Gamma(t \to c l_{j}^{+} l_{k}^{-})$ and the total width of the neutrino mode $ \Gamma(t \to c \tilde{\nu}' \nu)= \sum_{j,k} \Gamma(t \to c \tilde{\nu_{j}} \nu_{k})$ are found. The corresponding branching ratios are shown to be $ Br(t \to c {l^{+}}' l^{-}) \approx (3.5 - 0.4) 10^{-5}, $ $ Br(t \to c {\tilde{\nu}}' \nu) \approx (7.1 - 0.8) 10^{-5} $ for the scalar leptoquark masses $ m_{S}= 180 - 250 GeV $ and for the appropriate values $ (\sin{\beta} \approx 0.2) $ of the mixing angle of the model. The search for such decays at LHC may be of interest. 
P. Yu. Popov, A. D. Smirnov (Yaroslavl State University, Russia)