When energy goes missing: new physics in b → sνν with sterile neutrinos

Belle II recently reported the first measurement of B${}^{+}$ → K${}^{+}$ + inv, which is 2.8σ above the Standard Model prediction. We explore the available parameter space of new physics within Standard Model effective field theory extended by sterile neutrinos (νSMEFT) and provide predictions for the other B → K${}^{(\star )}$ + inv decay modes and invisible B${}_s$ decays. We also briefly comment on charged current decays B → D${}^{(\star )}\ell \overline{\nu }$ and possible ultraviolet completions of the relevant νSMEFT operators.