Enhancement of the Λb decay rate

The enhancement ΔΓ(Λb) of the Λb decay rate due to four-fermion processes of weak scattering and Pauli interference is calculated within the quark model. An estimate of the relative bu wave function at zero separation, |Ψ(0)|bu2, is ob in terms of the Σb∗ − Σb hyperfine splitting, the B∗ − B hyperfine splitting, and the B meson decay constant fB. For M(Σb∗ − M(Σb) = 56±16 MeV, M(B∗) − M(B) = 46 MeV, and fB = 190±40 MeV, we find ΔΓ(Λb) = (0.025±0.013) ps−1, to be compared with the observed enhancement Γ(Λb) − Γ(B0) = 0.20±0.05 ps−1. Even such a meager enhancement entails a value of |Ψ(0)|bu2 considerably larger than the corresponding value of |Ψ(0)|cd2 in t baryon.The enhancement ΔΓ(Λb) of the Λb decay rate due to four-fermion processes of weak scattering and Pauli interference is calculated within the quark model. An estimate of the relative bu wave function at zero separation, |Ψ(0)|bu2, is ob in terms of the Σb∗ − Σb hyperfine splitting, the B∗ − B hyperfine splitting, and the B meson decay constant fB. For M(Σb∗ − M(Σb) = 56±16 MeV, M(B∗) − M(B) = 46 MeV, and fB = 190±40 MeV, we find ΔΓ(Λb) = (0.025±0.013) ps−1, to be compared with the observed enhancement Γ(Λb) − Γ(B0) = 0.20±0.05 ps−1. Even such a meager enhancement entails a value of |Ψ(0)|bu2 considerably larger than the corresponding value of |Ψ(0)|cd2 in t baryon.