Observation of Bs0 → D 0 KS0 and Evidence for Bs0 → D ∗0 KS0 Decays

The first observation of the Bs0→D0KS0 decay mode and evidence for the Bs0→D∗0KS0 decay mode are reported. The data sample corresponds to an integrated luminosity of 3.0 fb-1 collected in pp collisions by LHCb at center-of-mass energies of 7 and 8 TeV. The branching fractions are measured to be B(Bs0→D0K0)=[4.3±0.5(stat)±0.3(syst)±0.3(frag)±0.6(norm)]×10-4,B(Bs0→D∗0K0)=[2.8±1.0(stat)±0.3(syst)±0.2(frag)±0.4(norm)]×10-4,where the uncertainties are due to contributions coming from statistical precision, systematic effects, and the precision of two external inputs, the ratio fs/fd and the branching fraction of B0→D0KS0, which is used as a calibration channel.