Targets for flavor-violating top decays

A bstract Analyticity and unitarity constrain certain classes of new physics models by linking flavor-conserving and flavor-violating four-fermion interactions. In this work, we explore how these theoretical relations impact flavor-violating rare top quark decays. Building on our previous results, we present an updated analysis of the decays t → qℓ + ℓ − and identify interesting target branching ratios in the range of 10 − 7 to 10 − 6 once current experimental constraints from flavor-conserving processes are taken into account. We extend the analysis to top decays with lepton flavor violation, deriving correlations among the relevant Wilson coefficients and confronting them with existing limits from LEP and the LHC. Notably, we find that current searches for t → qeμ are already probing theoretically motivated regions of parameter space. These results strongly support continued efforts to explore flavor-violating top decays as a powerful probe of new physics.