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Abstract:We search for CP violation in the decay D + → K 0 S K + using a data sample with an integrated luminosity of 977 fb −1 collected with the Belle detector at the KEKB e + e − asymmetric-energy collider. No CP violation has been observed and the CP asymmetry in D + → K 0 S K + decay is measured to be (−0.25 ± 0.28 ± 0.14)%, which is the most sensitive measurement to date. After subtracting CP violation due to K 0 −K 0 mixing, the CP asymmetry in D + →K 0 K + decay is found to be (+0.08 ± 0.28 ± 0.14)%.

We report results on the search for B s → η η decay, and the searches for B 0 → invisible and B 0 → invisible + γ decays. The former result is based on a data sample of 121.4 fb −1 recorded at the Υ(5S) resonance while the later results are obtained from a 711 fb −1 of data sample collected at Υ(4S) resonance with the Belle detector at the KEKB e + e − collider. We observe no significant signal for the decays and set upper limit on their branching fractions at 90% confidence level of B(B s → η η) < 7.1 × 10 −5 , B(B 0 → invisible) < 7.8 × 10 −5 and B(B 0 → invisible + γ) < 1.6 × 10 −5 .

We report on absolute lifetime measurements of charmed hadrons using the data collected by the Belle II experiment between 2019 and 2021. The measured lifetimes of 𝐷 0 , 𝐷 + , and Λ + 𝑐 are the most precise to date and consistent with previous measurements. Our result indicates that Ω 0 𝑐 is not the shortest-living singly charmed baryon.