Search For B�'J/Ψ+baryon+anti-baryon And B�'J/Ψη'K At Belle

Using a large data sample collected at the Î¥(4S) resonance with the Belle detector at the KEKB asymmetric energy e⁺e^- collider, we search for the following B meson decay modes:(1)To search for source of the excess in the low momentum region of the inclusive J/Ψ momentum spectrum for B → J/Ψ + X, which is not consistent with the predictions from nonrelativistic QCD calculation; to search for bound state of baryons and anti-baryons (baryonia); and search for new baryonic B decay mode. We perform searches for B → J/Ψ + baryon + anti-baryon decays (include B^- → J/Ψ Λ(?), B^-→ J/Ψ∑⁰(?) and B⁰ → J/Ψp(?)) using a data sample of 253 fb^-1 (275 million B(?) pairs).Candidates for B^-→ J/ΨΛ(?) and B⁰→ J/Ψp(?) are fully reconstructed with all daughters in the final states, where we use the decay chains J/Ψ → l⁺l^- (l = e,μ) and A → pÏ€^-. Candidates for B^-→ J/Ψ∑⁰(?) are reconstructed partially, where only the daughters from the J/Ψ and Λ decays plus the anti-proton are reconstructed in the final state. The A originates from the ∑⁰ →ΛΥ decay. Partial reconstruction of B^-→ J/Ψ∑⁰(?) without the low momentum Î¥ from the ∑⁰ decay gives better sensitivity than full reconstruction because of the low detection efficiency for soft photons. As a result, the same selection criteria are applied for fully reconstructed B^- → J/ΨΛ(?) and partially reconstructed B -→ J/Ψ∑⁰(?).The mass of daughter particles are very large for these three decay modes, sum of these masses is close to B meson mass. It make the momentum and reconstruction efficiency very low.We study reconstruction efficiency, signal region and event selection criteria using a large Monte Calor (MC) sample. To study background, we use inclusive J/Ψ MC (100 times that of real data) and sideband region of real data.Firstly, we process event selection and reconstruction (reconstruct J/Ψ and Λ, select (?) from charged track). B meson is reconstructed by combining selected and reconstructed daughter particle. We identify B candidates using two kinematic variables calculated in the center-of-mass system: the beam-energy constrained mass...