Observation of Λb0 → D ⁺ pπ⁻ π⁻ and Λb0 → D ^*+ pπ⁻ π⁻ decays

The multihadron decays Λb0 → D+pπ−π− and Λb0 → D^*+pπ−π− are observed in data corresponding to an integrated luminosity of 3 fb⁻¹, collected in proton-proton collisions at centre-of-mass energies of 7 and 8 TeV by the LHCb detector. Using the decay Λb0 → Λc+π⁺π⁻π⁻ as a normalisation channel, the ratio of branching fractions is measured to beB(Λb0→D+pπ−π−)B(Λb0→Λc0π+π−π−)×B(D+→K−π+π+)B(Λc0→pK−π−)=(5.35±0.21±0.16)%, where the first uncertainty is statistical and the second systematic. The ratio of branching fractions for the Λb0 → D^*+pπ⁻π⁻ and Λb0 → D⁺pπ⁻π⁻ decays is found to beB(Λb0→D∗+pπ−π−)B(Λb0→D+pπ−π−)×(B(D∗+→D+π0)+B(D∗+→D+γ))=(61.3±4.3±4.0)%.