LHCb Collaboration Reports First Observation of New Particle Decays

The LHCb collaboration has reported the first observation of the decays (\Lambda_{b}^{0} \rightarrow \Sigma_c^{()++} D^{()-} K^{-}) using data from proton-proton collisions at a center-of-mass energy of 13 TeV. This observation was made with an integrated luminosity of 6 fb^-1.

The study measured several branching fraction ratios, using the decay (\Lambda_b^0 \rightarrow \Lambda_c^{+} \overline{D}^0 K^{-}) as a reference channel. The results are as follows:

• (\frac{\mathcal{B} (\Lambda_{b}^{0} \rightarrow \Sigma_{c}^{++} D^{-} K^{-})}{\mathcal{B}(\Lambda_{b}^{0} \rightarrow \Lambda_c^{+} \overline{D}^0 K^{-})} = 0.282 \pm 0.016 \pm 0.016 \pm 0.005)
• (\frac{\mathcal{B}(\Lambda_{b}^{0} \rightarrow \Sigma_{c}^{*++} D^{-} K^{-})}{\mathcal{B}(\Lambda_{b}^{0} \rightarrow \Sigma_c^{++} D^{-} K^{-})} = 0.460 \pm 0.052 \pm 0.028)
• (\frac{\mathcal{B}(\Lambda_{b}^{0} \rightarrow \Sigma_{c}^{++} D^{-} K^{-})}{\mathcal{B}(\Lambda_{b}^{0} \rightarrow \Sigma_c^{++} D^{-} K^{-})} = 2.261 \pm 0.202 \pm 0.129 \pm 0.046)
• (\frac{\mathcal{B}(\Lambda_{b}^{0} \rightarrow \Sigma_{c}^{*++} D^{-} K^{-})}{\mathcal{B}(\Lambda_{b}^{0} \rightarrow \Sigma_c^{++} D^{-} K^{-})} = 0.896 \pm 0.137 \pm 0.066 \pm 0.018)

The uncertainties in these measurements include statistical, systematic, and those arising from the branching fractions of intermediate particle decays. This research contributes to the understanding of particle decays and may have implications for the study of the Standard Model of particle physics.

The findings are detailed in the paper titled "First observation of (\Lambda_{b}^{0} \rightarrow \Sigma_c^{()++} D^{()-} K^{-}) decays" by R. Aaij et al., available on Arxiv.org.