Observation of the decay $Λ_b^0 \to Λ_c^+ p \overline{p} π^-$

Abstract

The decay $Λ_b^0 \to Λ_c^+ p \overline{p} π^-$ is observed using $pp$ collision data collected with the LHCb detector at centre-of-mass energies of $\sqrt{s}=$ 7 and 8 TeV, corresponding to an integrated luminosity of 3 $fb^{-1}$. The ratio of branching fractions between $Λ_b^0 \to Λ_c^+ p \overline{p} π^-$ and $Λ_b^0 \to Λ_c^+ π^-$ decays is measured to be \begin{equation*} \frac{\mathcal{B}(Λ_b^0 \to Λ_c^+ p \overline{p}π^-)}{\mathcal{B}(Λ_b^0 \to Λ_c^+ π^-)} = 0.0540 \pm 0.0023 \pm 0.0032. \end{equation*} Two resonant structures are observed in the $ Λ_c^+ π^-$ mass spectrum of the ${Λ_b^0 \to Λ_c^+ p\overline{p} π^-}$ decays, corresponding to the $Σ_c(2455)^0$ and $Σ_c^{*}(2520)^0$ states. The ratios of branching fractions with respect to the decay $Λ_b^0 \to Λ_c^+ p \overline{p} π^-$ are \begin{align*} \frac{\mathcal{B}(Λ_b^0 \to Σ_c^0 p\overline{p})\times\mathcal{B}(Σ_c^0\to Λ_c^+ π^-)}{\mathcal{B}(Λ_b^0 \to Λ_c^+ p \overline{p}π^-)} = 0.089\pm0.015\pm0.006, \frac{\mathcal{B}(Λ_b^0 \to Σ_c^{*0} p\overline{p})\times\mathcal{B}(Σ_c^{*0}\to Λ_c^+ π^-)}{\mathcal{B}(Λ_b^0 \to Λ_c^+ p \overline{p}π^-)} = 0.119\pm0.020\pm0.014. \end{align*} In all of the above results, the first uncertainty is statistical and the second is systematic. The phase space is also examined for the presence of dibaryon resonances. No evidence for such resonances is found.

All figures and tables, along with any supplementary material and additional information, are available at https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2018-005.html