Exploring observable effects of scalar operators beyond SMEFT in the angular distribution of B→ K*0 τ⁺ τ⁻

The SU(2)L× U(1)Y invariance of the Standard Model Effective Field Theory (SMEFT) imposes relations among different low-energy effective field theory Wilson coefficients (WCs), any deviations from which would signal the presence of physics beyond SMEFT. In this work, we investigate two such relations (CS = -CP, CS^ = CP^) among the scalar and the pseudoscalar new-physics WCs that can contribute to b→ s \,τ τ processes. We show that, even when new physics violating these relations would not be measurable in the branching ratios of Bₛ → τ⁺ τ⁻ and B→ K(*)\,τ⁺ τ⁻ at HL-LHC and FCC-ee, it can still manifest itself in the angular distribution of B→ K*0\,τ⁺ τ⁻. We identify the combinations of angular observables in this decay channel that are sensitive to scenarios beyond SMEFT. We find that the two observables S₆ᶜ and A₇, and their combination, have the potential to identify physics beyond SMEFT.