NLO QCD corrections to full off-shell production of $$ t\overline{t}Z $$ including leptonic decays

Motivated by ongoing new physics searches in the top-quark sector at Large Hadron Collider we report on calculation of NLO QCD corrections to Standard Model $pp\to t\bar{t}Z+X$ process tetra-lepton decay channel. This is based matrix elements for $e^+ \nu_e\, \mu^-\bar{\nu}_\mu\, b\bar{b} \,\tau^+\tau^-$ final state and includes all resonant non-resonant Feynman diagrams, interferences off-shell effects top quark as well $W$ $Z$ gauge bosons. Also incorporated are photon-induced contributions. As it customary such studies, show theoretical predictions both fixed dynamical factorisation renormalisation scale choices different PDF sets. Furthermore, study main uncertainties that associated with neglected higher-order terms perturbative expansion parameterisation In order investigate size decays, perform a second computation this process, which narrow-width-approximation where quarks, bosons kept on-shell. Results given integrated differential fiducial cross sections LHC Run II center-of-mass energy $13$ TeV.