First observation of the Λ0𝑏� → D+D−Λ decay

Abstract

The Λ0𝑏 → 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−𝐾0𝑆 decay as a reference channel, the product of the relative production cross-section and decay branching fractions is measured to be

=σΛ0𝑏σ𝐵0=(Λ0𝑏→𝐷+𝐷−Λ)(𝐵0→𝐷+𝐷−𝐾0S)=0.179±0.022±0.014, where the first uncertainty is statistical and the second is systematic. The known branching fraction of the reference channel, (𝐵0→𝐷+𝐷−𝐾0S) , and the cross-section ratio, σΛ0𝑏/σ𝐵0 , previously measured by LHCb are used to derive the branching fraction of the Λ0𝑏 → D+D−Λ decay

(Λ0𝑏→𝐷+𝐷−Λ)=(1.24±0.15±0.10±0.28±0.11)×10−4, where the third and fourth contributions are due to uncertainties of (𝐵0→𝐷+𝐷−𝐾0S) and σΛ0𝑏/σ𝐵0 , respectively. Inspection of the D+Λ and D+D− invariant-mass distributions suggests a rich presence of intermediate resonances in the decay. The Λ0𝑏 → D*+D−Λ decay is also observed for the first time as a partially reconstructed component in the D+D−Λ invariant mass spectrum.