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

The multihadron decays Lambda(0)(b) -> D(+)p pi(-)pi(-) and Lambda(0)(b) -> D-*+p pi(-)pi(-) are observed in data corresponding to an integrated luminosity of 3fb(-1), collected in proton-proton collisions at centre-of-mass energies of 7 and 8 TeV by the LHCb detector. Using the decay Lambda(0)(b) -> Lambda(+)(c)pi(+)pi(-)pi(-) as a normalisation channel, the ratio of branching fractions is measured to be B(Lambda(0)(b) -> D(+)p pi(-)pi(-))/B(Lambda(0)(b) -> Lambda(+)(c)pi(+)pi(-)pi(-)) x B(D+ -> K-pi(+)pi(+))/B(Lambda(+)(c)-> pK(-)pi(+)) = (5.35 +/- 0.21 +/- 0.16) %, where the first uncertainty is statistical and the second systematic. The ratio of branching fractions for the Lambda(0)(b) -> D-*+p pi(-)pi(-) and Lambda(0)(b) -> D(+)p pi(-)pi(-) decays is found to be B(Lambda(0)(b) -> D-*+p pi(-)pi(-))/B(Lambda(0)(b) -> D(+)p pi(-)pi(-)) x (B(D-*+-> D+pi(0)) + B(D-*+ -> D+gamma)) = (61.3 +/- 4.3 +/- 4.0) %.