Measurements of the branching fractions of Ξc⁰→Ξ⁰π⁰, Ξc⁰→Ξ⁰η, and Ξc⁰→Ξ⁰η^ and asymmetry parameter of Ξc⁰→Ξ⁰π⁰

We present a study of Ξc⁰→Ξ⁰π⁰, Ξc⁰→Ξ⁰η, and Ξc⁰→Ξ⁰η^ decays using the Belle and Belle~II data samples, which have integrated luminosities of 980~fb⁻¹ and 426~fb⁻¹, respectively. We measure the following relative branching fractions B(Ξc⁰→Ξ⁰π⁰)/ B(Ξc⁰→Ξ⁻π⁺) = 0.48 ± 0.02 ( stat) ± 0.03 ( syst) , B(Ξc⁰→Ξ⁰η)/ B(Ξc⁰→Ξ⁻π⁺) = 0.11 ± 0.01 ( stat) ± 0.01 ( syst) , B(Ξc⁰→Ξ⁰η^)/ B(Ξc⁰→Ξ⁻π⁺) = 0.08 ± 0.02 ( stat) ± 0.01 ( syst) for the first time, where the uncertainties are statistical (stat) and systematic (syst). By multiplying by the branching fraction of the normalization mode, B(Ξc⁰→Ξ⁻π⁺), we obtain the following absolute branching fraction results (6.9 ± 0.3 ( stat) ± 0.5 ( syst) ± 1.3 ( norm)) × 10⁻³, (1.6 ± 0.2 ( stat) ± 0.2 ( syst) ± 0.3 ( norm)) × 10⁻³, and (1.2 ± 0.3 ( stat) ± 0.1 ( syst) ± 0.2 ( norm)) × 10⁻³, for Ξc⁰ decays to Ξ⁰π⁰, Ξ⁰η, and Ξ⁰η^ final states, respectively. The third errors are from the uncertainty on B(Ξc⁰→Ξ⁻π⁺). The asymmetry parameter for Ξc⁰→Ξ⁰π⁰ is measured to be α(Ξc⁰→Ξ⁰π⁰) = -0.90±0.15( stat)±0.23( syst).