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

The Λ_b⁰ → 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 B⁰ → D⁺D⁻K_S⁰ 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, BB⁰→D⁺D⁻K_S⁰, and the cross-section ratio, σΛ_b0/σB₀, previously measured by LHCb are used to derive the branching fraction of the Λ_b⁰→ D⁺D⁻Λ decay (Formula presented.) where the third and fourth contributions are due to uncertainties of BB⁰→D⁺D⁻K_S⁰ and σΛ_b0/σB₀, respectively. Inspection of the D⁺Λ and D⁺D⁻ invariant-mass distributions suggests a rich presence of intermediate resonances in the decay. The Λ_b⁰ → D^*+D⁻Λ decay is also observed for the first time as a partially reconstructed component in the D⁺D⁻Λ invariant mass spectrum.