Measurement of the branching fraction $\mathcal{B}({\mathrm{\Lambda }}_b^0\to {\mathrm{\Lambda }}_c^{+}{\pi }^{-}{\pi }^{+}{\pi }^{-})$ at CDF

We report an analysis of the ${\mathrm{\Lambda }}_b^0\to {\mathrm{\Lambda }}_c^{+}{\pi }^{-}{\pi }^{+}{\pi }^{-}$ decay in a data sample collected by the CDF II detector at the Fermilab Tevatron corresponding to 2.4 fb${}^{-1}$ of integrated luminosity. We reconstruct the currently largest samples of the decay modes ${\mathrm{\Lambda }}_b^0\to {\mathrm{\Lambda }}_c(2595{)}^{+}{\pi }^{-}$ (with ${\mathrm{\Lambda }}_c(2595{)}^{+}\to {\mathrm{\Lambda }}_c^{+}{\pi }^{+}{\pi }^{-}$), ${\mathrm{\Lambda }}_b^0\to {\mathrm{\Lambda }}_c(2625{)}^{+}{\pi }^{-}$ (with ${\mathrm{\Lambda }}_c(2625{)}^{+}\to {\mathrm{\Lambda }}_c^{+}{\pi }^{+}{\pi }^{-}$), $\Lambda^0_b\rightarrow \Sigma_c(2455)^{++}\pi^-\pi^-$(with$\Sigma_c(2455)^{++}\rightarrow\Lambda^+_c\pi^+$),and$\Lambda^0_b\rightarrow \Sigma_c(2455)^0\pi^+\pi^-$(with$\Sigma_c(2455)^0\rightarrow\Lambda^+_c \pi^-$)andmeasurethebranchingfractionsrelativetothe$\Lambda^0_b\rightarrow\Lambda^+_c\pi^-$ branching fraction. We measure the ratio $\BR(\Lambda^0_b\rightarrow \Lambda^+_c\pi^-\pi^+\pi^-) /\BR(\Lambda^0_b\rightarrow \Lambda^+c \pi^-) = 3.04 \pm 0.33($\text{stat}$)^{+0.70}{-0.55}($\text{syst}$)$whichisusedtoderive$\BR(\Lambda^0_b\rightarrow \Lambda^+c\pi^-\pi^+\pi^-)= (26.8^{+11.9}{-11.2})\times10^{-3}$.