Measurements of the branching fractions of Ξ_c^0→Ξ^0π^0, Ξ_c^0→Ξ^0η, and Ξ_c^0→Ξ^0η^' and asymmetry parameter of Ξ_c^0→Ξ^0π^0

We present a study of Ξ_c^0→Ξ^0π^0, Ξ_c^0→Ξ^0η, and Ξ_c^0→Ξ^0η^' 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(Ξ_c^0→Ξ^0π^0)/ B(Ξ_c^0→Ξ^-π^+) = 0.48 ± 0.02 ( stat) ± 0.03 ( syst) , B(Ξ_c^0→Ξ^0η)/ B(Ξ_c^0→Ξ^-π^+) = 0.11 ± 0.01 ( stat) ± 0.01 ( syst) , B(Ξ_c^0→Ξ^0η^')/ B(Ξ_c^0→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(Ξ_c^0→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 Ξ_c^0 decays to Ξ^0π^0, Ξ^0η, and Ξ^0η^' final states, respectively. The third errors are from the uncertainty on ℬ(Ξ_c^0→Ξ^-π^+). The asymmetry parameter for Ξ_c^0→Ξ^0π^0 is measured to be α(Ξ_c^0→Ξ^0π^0) = -0.90±0.15( stat)±0.23( syst).