Rare top decay t-> c l+l- as a probe of new physics
  The rare top decay t-> c l+l-, which involves flavor violation, is studied as a possible probe of new physics. This decay is analyzed with the simplest Standard Model extensions with additional gauge symmetry formalism. The considered extension is the Left-Right Symmetric Model, including a new neutral gauge boson Z' that allows to obtain the decay at tree level through Flavor Changing Neutral Currents (FCNC) couplings. The neutral gauge boson couplings are considered diagonal but family non-universal in order to induce these FCNC. We find the $BR(t-> c l+l-)~10^{-13} for a range 1 TeV < M_{Z'} < 3 TeV. 
J.L. Diaz-Cruz, A. Diaz-Furlong, R. Gaitan-Lozano and J.H. Montes de   Oca Y
hep-ph