Oscillations of $B_s^0$ mesons as a probe of decays with unreconstructed particles

JHEP 02 (2020) 163 A new experimental technique to study the decays of $B^0_s$ mesons into final states involving unreconstructable particles is proposed. The method uses a characteristic feature of fast flavour oscillations of $B^0_s$ mesons. Analysis of the oscillation-frequency spectrum of partially reconstructed flavour-tagged $B^0_s$ decays provides information about the mass spectrum of unreconstructed decay products and suppresses any background that does not come from the decays of $B^0_s$ mesons.