First Measurement of the ${\Lambda }_c^{+}\to p{\eta }^{\prime }$ decay

Abstract

We present the first measurement of the branching fraction of the singly Cabibbo-suppressed (SCS) decay ${\Lambda }_c^{+}\to p{\eta }^{\prime }$ with ${\eta }^{\prime }\to \eta {\pi }^{+}{\pi }^{-}$, using a data sample corresponding to an integrated luminosity of 981 $\mathrm{f}{\mathrm{b}}^{-1}$, collected by the Belle detector at the KEKB $e^{+}$$e^{-}$ asymmetric-energy collider. A significant ${\Lambda }_c^{+}$ signal is observed for the first time with a signal significance of 5.4$\sigma$. The relative branching fraction with respect to the normalization mode ${\Lambda }_c^{+}\to p{K}^{-}{\pi }^{+}$ is measured to be \begin{equation*} \frac{{\cal B}(\Lambda_c^+ \to p \eta')}{{\cal B}(\Lambda_c^+ \to p K^-\pi^+)} = (7.54 \pm 1.32 \pm 0.75) \times 10^{-3}, \end{equation*} where the uncertainties are statistical and systematic, respectively. Using the world-average value of $\mathcal{B}({\Lambda }_c^{+}\to p{K}^{-}{\pi }^{+})=(6.28\pm 0.32)\times 10^{-2}$, we obtain \begin{equation*} {\cal B}(\Lambda_c^+ \to p \eta') = (4.73 \pm 0.82 \pm 0.47 \pm 0.24)\times 10^{-4}, \end{equation*} where the uncertainties are statistical, systematic, and from $\mathcal{B}({\Lambda }_c^{+}\to p{K}^{-}{\pi }^{+})$, respectively.

Comments: 14 pages, 2 figures, accepted for publication in JHEP