Observation of the B0s → D*±D∓ decay

A search for the B0sBs0 → 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 be

B(B0s→D∗±D∓)(B0→D∗±D∓)=0.137±0.017±0.002±0.006,B(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 B0sBs0 and B0 hadronisation fractions.