Nonleptonic two-body decays of single heavy baryons ΛQ, ΞQ, and ΩQ (Q=b, c) induced by W emission in the covariant confined quark model

摘要

We have made a survey of heavy-to-heavy and heavy-to-light nonleptonic heavy baryon two-body decays and have identified those decays that proceed solely via W -boson emission, i.e., via the tree graph contribution. Some sample decays are Ω b ? → Ω c ( * ) 0 ρ ? ( π ? ) , Ω b ? → Ω ? J / ψ ( η c ) , Ξ b 0 , ? → Ξ 0 , ? J / ψ ( η c ) , Λ b → Λ J / ψ ( η c ) , Λ b → Λ c D s ( * ) , Ω c 0 → Ω ? ρ + ( π + ) , and Λ c → p ? . We make use of the covariant confined quark model previously developed by us to calculate the tree graph contributions to these decays. We calculate rates, branching fractions and, for some of these decays, decay asymmetry parameters. We compare our results to experimental findings and the results of other theoretical approaches when they are available. Our main focus is on decays to final states with a lepton pair because of their clean experimental signature. For these decays we discuss two-fold polar angle decay distributions such as in the cascade decay Ω b ? → Ω ? ( → Ξ π , Λ K ? ) + J / ψ ( → ? + ? ? ) . Lepton mass effects are always included in our analysis.