Observation of the B[superscript +] → D[superscript ∗] − K[superscript +] π[superscript +] decay

The B[superscript +]→D[superscript *-]K[superscript +]π[superscript +] decay potentially 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[superscript -1]. A clear signal is observed, and the ratio of its branching fraction to that of the B[superscript +]→D[superscript *-]π[superscript +]π[superscript +] normalization channel is measured to be B(B[superscript +]→D[superscript *-]K[superscript +]π[superscript +])/B(B[superscript +]→[superscript *-]π[superscript +]π[superscript +])=(6.39±0.27±0.48)×10[superscript -2], where the first uncertainty is statistical and the second is systematic. This is the first observation of the B[superscript +]→D[superscript *-]K[superscript +]π[superscript +] decay.