Observation of the Bs0 → D ^*± D ^∓ decay

A search for the Bs0→ D^*±D^∓ decay is performed using proton-proton collision data at centre-of-mass energies of 7, 8 and 13 TeV collected by the LHCb experiment, corresponding to an integrated luminosity of 9 fb⁻¹. The decay is observed with a high significance and its branching fraction relative to the B⁰→ D^*±D^∓ decay is measured to beℬ(Bs0→D∗±D∓)(B0→D∗±D∓)=0.137±0.017±0.002±0.006, where the first uncertainty is statistical, the second systematic and the third is due to the uncertainty on the ratio of the Bs0 and B⁰ hadronisation fractions. [Figure not available: see fulltext.]