First measurement of the Λ c + $$ {\Lambda}_c^{+} $$ → pη′ decay

Abstract We present the first measurement of the branching fraction of the singly Cabibbo-suppressed (SCS) decay Λ c + $$ {\Lambda}_c^{+} $$ → pη′ with η′ → ηπ + π − , using a data sample corresponding to an integrated luminosity of 981 fb −1, collected by the Belle detector at the KEKB e + e − asymmetric-energy collider. A significant Λ c + $$ {\Lambda}_c^{+} $$ → pη′ signal is observed for the first time with a signal significance of 5.4σ. The relative branching fraction with respect to the normalization mode Λ c + $$ {\Lambda}_c^{+} $$ → pK − π + is measured to be B Λ c + → pη ′ B Λ c + → pK − π + = 7.54 ± 1.32 ± 0.73 × 10 − 3 , $$ \frac{\mathcal{B}\left({\Lambda}_c^{+}\to p\eta^{\prime}\right)}{\mathcal{B}\left({\Lambda}_c^{+}\to {pK}^{-}{\pi}^{+}\right)}=\left(7.54\pm 1.32\pm 0.73\right)\times {10}^{-3}, $$ where the uncertainties are statistical and systematic, respectively. Using the world-average value of B Λ c + → pK − π + $$ \mathcal{B}\left({\Lambda}_c^{+}\to {pK}^{-}{\pi}^{+}\right) $$ = (6.28 ± 0.32) × 10 −2, we obtain B Λ c + → pη ′ = 4.73 ± 0.82 ± 0.46 ± 0.24 × 10 − 4 , $$ \mathcal{B}\left({\Lambda}_c^{+}\to p\eta^{\prime}\right)=\left(4.73\pm 0.82\pm 0.46\pm 0.24\right)\times {10}^{-4}, $$ where the uncertainties are statistical, systematic, and from B Λ c + → pK − π + $$ \mathcal{B}\left({\Lambda}_c^{+}\to {pK}^{-}{\pi}^{+}\right) $$ , respectively.