Measurement of the Decays ${\mathrm{\Lambda }}_c\to \mathrm{\Sigma }\pi \pi$ at Belle

We report measurements of the branching fractions of the decays ${\mathrm{\Lambda }}_c^{+}\to {\mathrm{\Sigma }}^{+}{\pi }^{-}{\pi }^{+}$, ${\mathrm{\Lambda }}_c^{+}\to {\mathrm{\Sigma }}^0{\pi }^{+}{\pi }^0$ and ${\mathrm{\Lambda }}_c^{+}\to {\mathrm{\Sigma }}^{+}{\pi }^0{\pi }^0$ relative to the reference channel ${\mathrm{\Lambda }}_c^{+}\to p{K}^{-}{\pi }^{+}$. The analysis is based on the full data sample collected at and close to $\mathrm{{\rm Y}}(4S)$ resonance by the Belle detector at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider corresponding to the integrated luminosity of 711 fb${}^{-1}$. We measure ${\cal B}(\Lambda^+_c\rightarrow\Sigma^+\pi^-\pi^+)/{\cal B}(\Lambda^+_c\to pK^-\pi^+) = 0.706~\pm 0.003~\pm 0.029$,${\cal B}(\Lambda^+_c\rightarrow\Sigma^0\pi^+\pi^0)/{\cal B}(\Lambda^+_c\to pK^-\pi^+) = 0.491~\pm 0.005~\pm 0.028$and${\cal B}(\Lambda^+_c\rightarrow\Sigma^+\pi^0\pi^0)/{\cal B}(\Lambda^+_c\to pK^-\pi^+) = 0.198~\pm 0.006~\pm 0.016$. The listed uncertainties are statistical and systematic, respectively.