Searches for anomalous $tqZ$ couplings from the trilepton signal of $tZ$ associated production at the 14 TeV LHC

We investigate the observability of the top anomalous $tqZ$ couplings via the trilepton signatures at the Large Hadron Collider~(LHC) with the center-of-mass energy of 14 TeV. We focus on signals of the $tZ$ associated production with the decay mode $t\to W^{+}b\to b{\mathrm{\ell }}^{+}{\nu }_{\mathrm{\ell }}$, $Z\to {\mathrm{\ell }}^{+}{\mathrm{\ell }}^{-}$, and $t\bar{t}$ production with the decay mode $\bar{t}\to Z(\to \ell^{+}\ell^{-})\bar{q}$and$t\to b\ell^{+}\nu_{\ell}$,where$\ell=e, \mu$and$q$reflectsupandcharmquarks\mathrm{.}Itisshownthatat$3\sigma$ level, the FCNC top quark decay branching ratios can be probed at, respectively, about $Br(t\to uZ)\le 1.3\times {10}^{-4}$ and $Br(t\to cZ)\le 4.2\times {10}^{-4}$ with the integrated luminosity of 100 fb${}^{-1}$, and probed down to $Br(t\to uZ) \leq 2.2\times 10^{-5}$and$Br(t\to cZ) \leq 8\times 10^{-5}$ for the high-luminosity LHC with 3000 fb${}^{-1}$.