We report a study of ${\mathrm{\Lambda }}_c^{+}\to {\mathrm{\Sigma }}^{+}{\pi }^0$, ${\mathrm{\Lambda }}_c^{+}\to {\mathrm{\Sigma }}^{+}\eta$, and ${\mathrm{\Lambda }}_c^{+}\to {\mathrm{\Sigma }}^{+}{\eta }^{\prime }$ using the data sample corresponding to an integrated luminosity of $980{\mathrm{fb}}^{-1}$ collected with the Belle detector at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider. The branching fractions relative to ${\mathrm{\Lambda }}_c^{+}\to {\mathrm{\Sigma }}^{+}{\pi }^0$ are measured as ${\mathcal{B}}_{{\mathrm{\Lambda }}_c^{+}\to {\mathrm{\Sigma }}^{+}\eta }/{\mathcal{B}}_{{\mathrm{\Lambda }}_c^{+}\to {\mathrm{\Sigma }}^{+}{\pi }^0}=0.25\pm 0.03\pm 0.01$ and ${\mathcal{B}}_{{\mathrm{\Lambda }}_c^{+}\to {\mathrm{\Sigma }}^{+}{\eta }^{\prime }}/{\mathcal{B}}_{{\mathrm{\Lambda }}_c^{+}\to {\mathrm{\Sigma }}^{+}{\pi }^0}=0.33\pm 0.06\pm 0.02$. Using ${\mathcal{B}}_{{\mathrm{\Lambda }}_c^{+}\to {\mathrm{\Sigma }}^{+}{\pi }^0}=(1.25\pm 0.10)\%$, we obtain ${\mathcal{B}}_{{\mathrm{\Lambda }}_c^{+}\to {\mathrm{\Sigma }}^{+}\eta }=(3.14\pm 0.35\pm 0.17\pm 0.25)\times {10}^{-3}$ and ${\mathcal{B}}_{{\mathrm{\Lambda }}_c^{+}\to {\mathrm{\Sigma }}^{+}{\eta }^{\prime }}=(4.16\pm 0.75\pm 0.25\pm 0.33)\times {10}^{-3}$. Here the uncertainties are statistical, systematic, and from ${\mathcal{B}}_{{\mathrm{\Lambda }}_c^{+}\to {\mathrm{\Sigma }}^{+}{\pi }^0}$, respectively. The ratio of the branching fraction of ${\mathrm{\Lambda }}_c^{+}\to {\mathrm{\Sigma }}^{+}{\eta }^{\prime }$ with respect to that of ${\mathrm{\Lambda }}_c^{+}\to {\mathrm{\Sigma }}^{+}\eta$ is measured to be ${\mathcal{B}}_{{\mathrm{\Lambda }}_c^{+}\to {\mathrm{\Sigma }}^{+}{\eta }^{\prime }}/{\mathcal{B}}_{{\mathrm{\Lambda }}_c^{+}\to {\mathrm{\Sigma }}^{+}\eta }=1.34\pm 0.28\pm 0.08$. We update the asymmetry parameter of ${\mathrm{\Lambda }}_c^{+}\to {\mathrm{\Sigma }}^{+}{\pi }^0$, ${\alpha }_{{\mathrm{\Sigma }}^{+}{\pi }^0}=-0.48\pm 0.02\pm 0.02$, with a considerably improved precision. The asymmetry parameters of ${\mathrm{\Lambda }}_c^{+}\to {\mathrm{\Sigma }}^{+}\eta$ and ${\mathrm{\Lambda }}_c^{+}\to {\mathrm{\Sigma }}^{+}{\eta }^{\prime }$ are measured to be ${\alpha }_{{\mathrm{\Sigma }}^{+}\eta }=-0.99\pm 0.03\pm 0.05$ and ${\alpha }_{{\mathrm{\Sigma }}^{+}{\eta }^{\prime }}=-0.46\pm 0.06\pm 0.03$ for the first time.

• Received 23 August 2022
• Accepted 8 December 2022

DOI:https://doi.org/10.1103/PhysRevD.107.032003

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Published by the American Physical Society