Flavor changing neutral current decays trightarrow c X (X=gamma ,,g,, Z,, H) and trightarrow c{{bar{ell }}}ell (ell =mu ,,tau ) via scalar leptoquarks

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The flavor changing neutral current decays trightarrow c X (X=gamma ,,g,, Z,, H) and trightarrow c{{bar{ell }}}ell (ell =mu ,,tau ) are studied in a renormalizable scalar leptoquark (LQ) model with no proton decay, where a scalar SU(2) doublet with hypercharge Y=7/6 is added to the standard model, yielding a non-chiral LQ varOmega _{5/3}. Analytical results for the one-loop (tree-level) contributions of a scalar LQ to the f_irightarrow f_j X (f_irightarrow f_j {bar{f}}_m f_l) decays, with f_a=q_a, ell _a, are presented. We consider the scenario where varOmega _{5/3} couples to the fermions of the second and third families, with its right- and left-handed couplings obeying lambda _R^{ell u_i}/lambda _L^{ell u_i}=O(epsilon ), where epsilon parametrizes the relative size between these couplings. The allowed parameter space is then found via the current constraints on the muon (g-2), the tau rightarrow mu gamma decay, the LHC Higgs boson data, and the direct LQ searches at the LHC. For m_{varOmega _{5/3}}=1 TeV and epsilon =10^{-3}, we find that the trightarrow c X branching ratios are of similar size and can be as large as 10^{-8} in a tiny area of the parameter space, whereas {mathrm{Br}}(trightarrow c{{bar{tau }}}tau ) [{mathrm{Br}}(trightarrow c{{bar{mu }}}mu )] can be up to 10^{-6} (10^{-7}).