First observation of the Λb0→ D ⁺D ⁻Λ decay

The Λ _b ⁰ → D ⁺D ⁻Λ decay is observed for the first time using proton-proton collision data collected by the LHCb experiment at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 5.3 fb ⁻¹. Using the B ⁰ → D ⁺D ⁻K _S ⁰ decay as a reference channel, the product of the relative production cross-section and decay branching fractions is measured to be (Formula presented.) where the first uncertainty is statistical and the second is systematic. The known branching fraction of the reference channel, BB ⁰→D ⁺D ⁻K _S ⁰, and the cross-section ratio, σΛ _{b 0}/σB ₀, previously measured by LHCb are used to derive the branching fraction of the Λ _b ⁰→ D ⁺D ⁻Λ decay (Formula presented.) where the third and fourth contributions are due to uncertainties of BB ⁰→D ⁺D ⁻K _S ⁰ and σΛ _{b 0}/σB ₀, respectively. Inspection of the D ⁺Λ and D ⁺D ⁻ invariant-mass distributions suggests a rich presence of intermediate resonances in the decay. The Λ _b ⁰ → D ^*+D ⁻Λ decay is also observed for the first time as a partially reconstructed component in the D ⁺D ⁻Λ invariant mass spectrum.