First observation of the ${\Lambda }_b^0\to D^{+}{D}^{-}\Lambda$ decay

Abstract

The ${\Lambda }_b^0\to D^{+}{D}^{-}\Lambda$ decay is observed for the first time using proton-proton collision data collected by the LHCb experiment at a center-of-mass energy of $13\mathrm{TeV}$, corresponding to an integrated luminosity of $5.3{\mathrm{fb}}^{-1}$. Using the $B^0\to D^{+}{D}^{-}{K}_{\mathrm{S}}^0$ decay as a reference channel, the product of the relative production cross-section and decay branching fractions is measured to be $$\mathcal{R}=\frac{{\sigma }_{{\Lambda }_b^0}}{{\sigma }_{B^0}}\times \frac{\mathcal{B}({\Lambda }_b^0\to D^{+}{D}^{-}\Lambda )}{\mathcal{B}(B^0\to D^{+}{D}^{-}{K}_{\mathrm{S}}^0)}=0.179\pm 0.022\pm 0.014$$ where the first uncertainty is statistical and the second is systematic. The known branching fraction of the reference channel, $\mathcal{B}(B^0\to D^{+}{D}^{-}{K}_{\mathrm{S}}^0)$, and the cross-section ratio, ${\sigma }_{{\Lambda }_b^0}/{\sigma }_{B^0}$, previously measured by $\mathrm{LHCb}$ are used to derive the branching fraction of the ${\Lambda }_b^0\to D^{+}{D}^{-}\Lambda$ decay $$\mathcal{B}({\Lambda }_b^0\to D^{+}{D}^{-}\Lambda )=(1.24\pm 0.15\pm 0.10\pm 0.28\pm 0.11)\times 10^{-4},$$ where the third and fourth contributions are due to uncertainties of $\mathcal{B}(B^0\to D^{+}{D}^{-}{K}_{\mathrm{S}}^0)$ and ${\sigma }_{{\Lambda }_b^0}/{\sigma }_{B^0}$, respectively. Inspection of the $D^{+}\Lambda$ and $D^{+}{D}^{-}$ invariant-mass distributions suggests a rich presence of intermediate resonances in the decay. The ${\Lambda }_b^0\to D^{\ast +}{D}^{-}\Lambda$ decay is also observed for the first time as a partially reconstructed component in the $D^{+}{D}^{-}\Lambda$ invariant mass spectrum.

All figures and tables, along with machine-readable versions and any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2023-042.html (LHCb public pages)

References in corpus (2)

• PYTHIA 6.4 Physics and Manual
• RapidSim: an application for the fast simulation of heavy-quark hadron decays

Cited by in corpus (2)

• Observation of the open-charm tetraquark candidate $T_{cs0}^{\ast }(2870{)}^0$ in the $B^{-}\to D^{-}{D}^0{K}_{\mathrm{S}}^0$ decay
• Towards replacing detector simulation with heterogeneous GNNs in flavour physics analyses