The Chromoelectric Dipole Moment of the Top Quark in Models with Vector   Like Multiplets
  The chromoelectric dipole moment of the top quark is calculated in a model with a vector like multiplet which mixes with the third generation in an extension of the MSSM. Such mixings allow for new CP violating phases. Including these new CP phases, the chromoelectric dipole moment that generates an electric dipole of the top in this class of models is computed. The top chromoelectric dipole moment operator arises from loops involving the exchange of the W, the Z as well as from the exchange involving the charginos, the neutralinos, the gluino, and the vector like multiplet and their superpartners. The analysis of the chromoelectric dipole moment operator of the top is more complicated than for the light quarks because the mass of the external fermion, in this case the top quark mass, cannot be ignored relative to the masses inside the loops. A numerical analysis is presented and it is shown that the contribution to the top EDM could lie in the range ($10^{-19}-10^{-18})$ ecm consistent with the current limits on the EDM of the electron, the neutron and on atomic EDMs. A top EDM of size $(10^{-19}-10^{-18})$ ecm could be accessible in collider experiments such as at the LHC and at the ILC. 
Tarek Ibrahim and Pran Nath
hep-ph hep-ex