Exploring observable effects of scalar operators beyond SMEFT in the angular distribution of B K^*0 ^+ ^-

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 \, processes. We show that, even when new physics violating these relations would not be measurable in the branching ratios of Bₛ ^+ ^- and B K^ (*) \, ^+ ^- at HL-LHC and FCC-ee, it can still manifest itself in the angular distribution of B K^*0\, ^+ ^-. 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.