Constraining the dipole moments of the top quark
  We investigate the direct and indirect bounds on dipole operators involving the top quark. A careful analysis shows that the experimental upper limit on the neutron electric dipole moment strongly constrains the chromo-electric dipole of the top. We improve previous bounds by two orders of magnitude. This has significant implications for new physics models and it also means that CP violation in top pair production mediated by dipole operators will not be accessible at the LHC. The CP conserving chromo-magnetic dipole moments are constrained by recent measurements of the t\bar t spectrum by the ATLAS collaboration. We also update the indirect constraints on electric and magnetic dipole moments from radiative b -> s transitions, finding that they can be considerably larger than their colored counterparts. 
Jernej F. Kamenik, Michele Papucci and Andreas Weiler
hep-ph