Observation of the B+→D-K+π+ decay

The B+→D*-K+π+decaypotentially provides an excellent way to investigate charm meson spectroscopy. The decay is searched for in a sample of proton-proton collision data collected with the LHCb detector at center-of-mass energies of 7 and 8 TeV, corresponding to an integrated luminosity of 3 fb-1 . A clear signal is observed, and the ratio of its branching fraction to that of the B+→D*-π+π+ normalization channel is measured to be B (B+→D*-K+π+)/B (B+→D*-π+π+)=(6.39 ±0.27 ±0.48 ) ×10-2, where the first uncertainty is statistical and the second is systematic. This is the first observation of the B+→D*-K+π+ decay.