A highly significant structure is observed in the Λ_{c}^{+}K^{-}π^{+}π^{+} mass spectrum, where the Λ_{c}^{+} baryon is reconstructed in the decay mode pK^{-}π^{+}. The structure is consistent with originating from a weakly decaying particle, identified as the doubly charmed baryon Ξ_{cc}^{++}. The difference between the masses of the Ξ_{cc}^{++} and Λ_{c}^{+} states is measured to be 1334.94±0.72(stat.)±0.27(syst.)  MeV/c^{2}, and the Ξ_{cc}^{++} mass is then determined to be 3621.40±0.72(stat.)±0.27(syst.)±0.14(Λ_{c}^{+})  MeV/c^{2}, where the last uncertainty is due to the limited knowledge of the Λ_{c}^{+} mass. The state is observed in a sample of proton-proton collision data collected by the LHCb experiment at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 1.7  fb^{-1}, and confirmed in an additional sample of data collected at 8 TeV.

The production of J/ψ mesons is studied in proton-lead collisions at the centre-of-mass energy per nucleon pair sNN=8.16 TeV with the LHCb detector at the LHC. The double differential cross-sections of prompt and nonprompt J/ψ production are measured as a function of the J/ψ transverse momentum and rapidity in the nucleon–nucleon centre-of-mass frame. Forward-to-backward ratios and nuclear modification factors are determined. The results are compared with theoretical calculations based on collinear factorisation using nuclear parton distribution functions, on the colour glass condensate or on coherent energy loss models.

A measurement of the shape of the differential decay rate and the associated Isgur-Wise function for the decay Λ0 b → Λ+c μ- νμ is reported, using data corresponding to 3 fb-1collected with the LHCb detector in proton-proton collisions. The Λ+c μ- νμ anything final states are reconstructed through the detection of a muon and a Λ+c baryon decaying into pK-π+, and the decays Λ0 b → Λ+c π+π-μ- νμ are used to determine contributions from Λ0 b → Λ0c μ- νμ decays. The measured dependence of the differential decay rate upon the squared four-momentum transfer between the heavy baryons, q2, is compared with expectations from heavy-quark effective theory and from unquenched lattice QCD predictions.

Production of prompt D0 mesons is studied in proton-lead and lead-proton collisions recorded at the LHCb detector at the LHC. The data sample corresponds to an integrated luminosity of 1.58±0.02 nb−1 recorded at a nucleon-nucleon centre-of-mass energy of sNN=5 TeV. Measurements of the differential cross-section, the forward-backward production ratio and the nuclear modification factor are reported using D0 candidates with transverse momenta less than 10 GeV/c and rapidities in the ranges 1.5 < y∗< 4.0 and −5.0 < y∗< −2.5 in the nucleon-nucleon centre-of-mass system.