Top and Beauty synergies in SMEFT-fits at present and future colliders

We perform global fits within Standard Model Effective Field Theory (SMEFT) combining top-quark pair production processes and decay with $b\to s$ flavor changing neutral current transitions and $Z\to b\bar{b}$ in three stages: using existing data from the LHC and $B$-factories, using projections for the HL-LHC and Belle II, and studying the additional new physics impact from a future lepton collider. The latter is ideally suited to directly probe ${\mathrm{\ell }}^{+}{\mathrm{\ell }}^{-}\to t\bar{t}$ transitions. We observe powerful synergies in combining both top and beauty observables as flat directions are removed and more operators can be probed. We find that a future lepton collider significantly enhances this interplay and qualitatively improves global SMEFT fits.