Measurements of new physics in top quark decay at LHC

A summary of ATLAS and CMS results on searches for new physics in top quark decay is presented. Three analysis are reported: the ATLAS and CMS searches for flavor changing neutral currents (FCNC) in top-quark decays and the CMS search for baryon number violation (BNV) in top-quark decays. ATLAS and CMS provided exclusion limits (at 95\% CL) on the FCNC decay $t \rightarrow Zq$, using respectively 2.1 $fb^{-1}$ and 5.0 $fb^{-1}$ of $pp$ collisions at $\sqrt{s}$ = 7 TeV collected in 2011. Upper limits on $B(t \rightarrow Zq)$ are respectively 0.73\% and 0.24\%. CMS has also set an exclusion limit (at 95\% CL) on the BNV decay $t \rightarrow lbq$ using 5.0 $fb^{-1}$ of data. Upper limit on $B(t \rightarrow lbq)$ is 0.67\%.