Measurements of branching fractions of Λc+→Σ+η and Λc+→Σ+η′ and asymmetry parameters of Λc+→Σ+π0, Λc+→Σ+η, and Λc+→Σ+η′

We report a study of Λ+c→Σ+π0, Λ+c→Σ+η, and Λ+c→Σ+η′ using the data sample corresponding to an integrated luminosity of 980 fb−1 collected with the Belle detector at the KEKB asymmetric-energy e+e− collider. The branching fractions relative to Λ+c→Σ+π0 are measured as: B(Λ+c→Σ+η)/B(Λ+c→Σ+π0)=0.25±0.03±0.01 and B(Λ+c→Σ+η′)/B(Λ+c→Σ+π0)=0.33±0.06±0.02. Using B(Λ+c→Σ+π0)=(1.25±0.10)%, we obtain B(Λ+c→Σ+η)=(3.14±0.35±0.11±0.25)×10^−3 and B(Λ+c→Σ+η′)=(4.16±0.75±0.21±0.33)×10^−3. Here the uncertainties are statistical, systematic, and from B(Λ+c→Σ+π0), respectively. The ratio of the branching fraction of Λ+c→Σ+η′ with respect to that of Λ+c→Σ+η is measured to be B(Λ+c→Σ+η′)/B(Λ+c→Σ+η)=1.34±0.28±0.06. We update the asymmetry parameter of Λ+c→Σ+π0, α(Σ+π0)=−0.48±0.02±0.02, with a considerably improved precision. The asymmetry parameters of Λ+c→Σ+η and Λ+c→Σ+η′ are measured to be α(Σ+η)=−0.99±0.03±0.05 and α(Σ+η′)=−0.46±0.06±0.03 for the first time.