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

Abstract

We perform global fits within Standard Model Effective Field Theory (SMEFT) combining top-quark pair production processes and decay with $b\rightarrow s$ 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 $\ell^+\ell^-\rightarrow t\bar t$ 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.