Measurements of branching fractions of ${\Lambda }_c^{+}\to {\Sigma }^{+}\eta$ and ${\Lambda }_c^{+}\to {\Sigma }^{+}{\eta }^{\prime }$ and asymmetry parameters of ${\Lambda }_c^{+}\to {\Sigma }^{+}{\pi }^0$, ${\Lambda }_c^{+}\to {\Sigma }^{+}\eta$, and ${\Lambda }_c^{+}\to {\Sigma }^{+}{\eta }^{\prime }$

Abstract

We report a study of ${\Lambda }_c^{+}\to {\Sigma }^{+}{\pi }^0$, ${\Lambda }_c^{+}\to {\Sigma }^{+}\eta$, and ${\Lambda }_c^{+}\to {\Sigma }^{+}{\eta }^{\prime }$ using the data sample corresponding to an integrated luminosity of 980 $\mathrm{f}{\mathrm{b}}^{-1}$ collected with the Belle detector at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider. The branching fractions relative to ${\Lambda }_c^{+}\to {\Sigma }^{+}{\pi }^0$ are measured as: ${\mathcal{B}}_{{\Lambda }_c^{+}\to {\Sigma }^{+}\eta }/{\mathcal{B}}_{{\Lambda }_c^{+}\to {\Sigma }^{+}{\pi }^0}=0.25\pm 0.03\pm 0.01$ and ${\mathcal{B}}_{{\Lambda }_c^{+}\to {\Sigma }^{+}{\eta }^{\prime }}/{\mathcal{B}}_{{\Lambda }_c^{+}\to {\Sigma }^{+}{\pi }^0}=0.33\pm 0.06\pm 0.02$. Using ${\mathcal{B}}_{{\Lambda }_c^{+}\to {\Sigma }^{+}{\pi }^0}=(1.25\pm 0.10)\%$, we obtain ${\mathcal{B}}_{{\Lambda }_c^{+}\to {\Sigma }^{+}\eta }=(3.14\pm 0.35\pm 0.11\pm 0.25)\times 10^{-3}$ and ${\mathcal{B}}_{{\Lambda }_c^{+}\to {\Sigma }^{+}{\eta }^{\prime }}=(4.16\pm 0.75\pm 0.21\pm 0.33)\times 10^{-3}$. Here the uncertainties are statistical, systematic, and from ${\mathcal{B}}_{{\Lambda }_c^{+}\to {\Sigma }^{+}{\pi }^0}$, respectively. The ratio of the branching fraction of ${\Lambda }_c^{+}\to {\Sigma }^{+}{\eta }^{\prime }$ with respect to that of ${\Lambda }_c^{+}\to {\Sigma }^{+}\eta$ is measured to be ${\mathcal{B}}_{{\Lambda }_c^{+}\to {\Sigma }^{+}{\eta }^{\prime }}/{\mathcal{B}}_{{\Lambda }_c^{+}\to {\Sigma }^{+}\eta }=1.34\pm 0.28\pm 0.06$. We update the asymmetry parameter of ${\Lambda }_c^{+}\to {\Sigma }^{+}{\pi }^0$, ${\alpha }_{{\Sigma }^{+}{\pi }^0}=-0.48\pm 0.02\pm 0.02$, with a considerably improved precision. The asymmetry parameters of ${\Lambda }_c^{+}\to {\Sigma }^{+}\eta$ and ${\Lambda }_c^{+}\to {\Sigma }^{+}{\eta }^{\prime }$ are measured to be ${\alpha }_{{\Sigma }^{+}\eta }=-0.99\pm 0.03\pm 0.05$ and ${\alpha }_{{\Sigma }^{+}{\eta }^{\prime }}=-0.46\pm 0.06\pm 0.03$ for the first time.

Comments: 12 pages, 8 figures; accepted for publication as a Regular Article in Physical Review D