Observation of the decays 𝐵 + → Σ 𝑐 (2455) ++ $\bar{Ξ}^-_c$ and 𝐵 0 → Σ 𝑐 (2455) 0 $\bar{Ξ}^0_𝑐$
We report the first observation of the two-body baryonic decays 𝐵 + → Σ 𝑐 (2455) ++ $\bar{Ξ}^-_c$ and 𝐵 0 → Σ 𝑐 (2455) 0 $\bar{Ξ}^0_𝑐$ with significances of 7.3𝜎 and 6.2𝜎, respectively, including statistical and systematic uncertainties. The branching fractions are measured to be ℬ(𝐵 + → Σ 𝑐 (2455) ++ $\bar{Ξ}^-_c$) = (5.74 ± 1.11 ± 0.42$^{+2.47}_{−1.53}$) ×10 −4 and ℬ(𝐵 0 → Σ 𝑐 (2455) 0 $\bar{Ξ}^0_𝑐$) = (4.83 ± 1.12 ± 0.37$^{+0.72}_{−0.60}$) ×10 −4 . The first and second uncertainties are statistical and systematic, respectively, while the third ones arise from the absolute branching fractions of $\bar{Ξ}^-_c$ or $\bar{Ξ}^0_𝑐$ decays. The data samples used for this analysis have integrated luminosities of 711 fb −1 and 365 fb −1 , and were collected at the ϒ(4𝑆) resonance by the Belle and Belle II detectors operating at the KEKB and SuperKEKB asymmetric-energy 𝑒 + 𝑒 − colliders, respectively.