Speaker
Description
We perform a global analysis of top-quark flavour-changing neutral current (FCNC) interactions and the dominant charged-current $(Wtb)$ coupling within an effective field theory framework, incorporating constraints from low-energy flavour observables, electroweak precision data, Higgs and gauge-boson measurements, and electric dipole moment (EDM) bounds. Beginning with a general parametrisation of the top-quark couplings, we match these interactions to the Standard Model Effective Field Theory (SMEFT) operator basis at the top-quark scale. By treating the top-dipole operators as complex, we derive stringent limits on both the real and imaginary parts of the top FCNC couplings. In addition, the bounds on the charged-current top-quark effective coupling $(Wtb)$ are significantly improved compared to the existing limits reported by ATLAS and CMS. Finally, we provide predictions for branching ratios and CP asymmetries in rare top-quark decays. We identify well-motivated benchmark scenarios for future collider searches and emphasise the crucial role of CP-violating effects in probing the flavour structure of the top quark.